// the structure of this file:
//
// [SECTION] Bézier curve helpers
// [SECTION] draw list helper
// [SECTION] ui state logic
// [SECTION] render helpers
// [SECTION] API implementation

#include "imnodes.hpp"

#include <imgui_internal.h>

#include "imnodes_internal.hpp"

// Check minimum ImGui version
#define MINIMUM_COMPATIBLE_IMGUI_VERSION 18200
#if IMGUI_VERSION_NUM < MINIMUM_COMPATIBLE_IMGUI_VERSION
#error "Minimum ImGui version requirement not met -- please use a newer version!"
#endif

#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <new>

// Use secure CRT function variants to avoid MSVC compiler errors
#ifdef _MSC_VER
#define sscanf sscanf_s
#endif

ImNodesContext* GImNodes = nullptr;

namespace ImNodes {
namespace {
// [SECTION] bezier curve helpers

struct CubicBezier {
  ImVec2 P0, P1, P2, P3;
  int NumSegments{};
};

inline ImVec2 EvalCubicBezier(
    const float t, const ImVec2& P0, const ImVec2& P1, const ImVec2& P2, const ImVec2& P3) {
  // B(t) = (1-t)**3 p0 + 3(1 - t)**2 t P1 + 3(1-t)t**2 P2 + t**3 P3

  const float u = 1.0F - t;
  const float b0 = u * u * u;
  const float b1 = 3 * u * u * t;
  const float b2 = 3 * u * t * t;
  const float b3 = t * t * t;
  return {
      b0 * P0.x + b1 * P1.x + b2 * P2.x + b3 * P3.x, b0 * P0.y + b1 * P1.y + b2 * P2.y + b3 * P3.y};
}

// Calculates the closest point along each Bézier curve segment.
ImVec2 GetClosestPointOnCubicBezier(
    const int num_segments, const ImVec2& p, const CubicBezier& cb) {
  IM_ASSERT(num_segments > 0);
  ImVec2 p_last = cb.P0;
  ImVec2 p_closest;
  float p_closest_dist = FLT_MAX;
  const float t_step = 1.0F / static_cast<float>(num_segments);
  for (int i = 1; i <= num_segments; ++i) {
    const ImVec2 p_current =
        EvalCubicBezier(t_step * static_cast<float>(i), cb.P0, cb.P1, cb.P2, cb.P3);
    const ImVec2 p_line = ImLineClosestPoint(p_last, p_current, p);
    const float dist = ImLengthSqr(p - p_line);
    if (dist < p_closest_dist) {
      p_closest = p_line;
      p_closest_dist = dist;
    }
    p_last = p_current;
  }
  return p_closest;
}

inline float GetDistanceToCubicBezier(
    const ImVec2& pos, const CubicBezier& cubic_bezier, const int num_segments) {
  const ImVec2 point_on_curve = GetClosestPointOnCubicBezier(num_segments, pos, cubic_bezier);

  const ImVec2 to_curve = point_on_curve - pos;
  return ImSqrt(ImLengthSqr(to_curve));
}

inline ImRect GetContainingRectForCubicBezier(const CubicBezier& cb) {
  const ImVec2 min = ImVec2(ImMin(cb.P0.x, cb.P3.x), ImMin(cb.P0.y, cb.P3.y));
  const ImVec2 max = ImVec2(ImMax(cb.P0.x, cb.P3.x), ImMax(cb.P0.y, cb.P3.y));

  const float hover_distance = GImNodes->Style.LinkHoverDistance;

  ImRect rect(min, max);
  rect.Add(cb.P1);
  rect.Add(cb.P2);
  rect.Expand(ImVec2(hover_distance, hover_distance));

  return rect;
}

inline CubicBezier GetCubicBezier(ImVec2 start,
    ImVec2 end,
    const ImNodesAttributeType start_type,
    const float line_segments_per_length) {
  IM_ASSERT(
      (start_type == ImNodesAttributeType_Input) || (start_type == ImNodesAttributeType_Output));
  if (start_type == ImNodesAttributeType_Input) {
    ImSwap(start, end);
  }

  const float link_length = ImSqrt(ImLengthSqr(end - start));
  const ImVec2 offset = ImVec2(0.25F * link_length, 0.F);
  CubicBezier cubic_bezier;
  cubic_bezier.P0 = start;
  cubic_bezier.P1 = start + offset;
  cubic_bezier.P2 = end - offset;
  cubic_bezier.P3 = end;
  cubic_bezier.NumSegments = ImMax(static_cast<int>(link_length * line_segments_per_length), 1);
  return cubic_bezier;
}

inline float EvalImplicitLineEq(const ImVec2& p1, const ImVec2& p2, const ImVec2& p) {
  return (p2.y - p1.y) * p.x + (p1.x - p2.x) * p.y + (p2.x * p1.y - p1.x * p2.y);
}

inline int Sign(float val) {
  return int(val > 0.0F) - int(val < 0.0F);
}

inline bool RectangleOverlapsLineSegment(const ImRect& rect, const ImVec2& p1, const ImVec2& p2) {
  // Trivial case: rectangle contains an endpoint
  if (rect.Contains(p1) || rect.Contains(p2)) {
    return true;
  }

  // Flip rectangle if necessary
  ImRect flip_rect = rect;

  if (flip_rect.Min.x > flip_rect.Max.x) {
    ImSwap(flip_rect.Min.x, flip_rect.Max.x);
  }

  if (flip_rect.Min.y > flip_rect.Max.y) {
    ImSwap(flip_rect.Min.y, flip_rect.Max.y);
  }

  // Trivial case: line segment lies to one particular side of rectangle
  if ((p1.x < flip_rect.Min.x && p2.x < flip_rect.Min.x) ||
      (p1.x > flip_rect.Max.x && p2.x > flip_rect.Max.x) ||
      (p1.y < flip_rect.Min.y && p2.y < flip_rect.Min.y) ||
      (p1.y > flip_rect.Max.y && p2.y > flip_rect.Max.y)) {
    return false;
  }

  const std::array<int, 4> corner_signs = {Sign(EvalImplicitLineEq(p1, p2, flip_rect.Min)),
      Sign(EvalImplicitLineEq(p1, p2, ImVec2(flip_rect.Max.x, flip_rect.Min.y))),
      Sign(EvalImplicitLineEq(p1, p2, ImVec2(flip_rect.Min.x, flip_rect.Max.y))),
      Sign(EvalImplicitLineEq(p1, p2, flip_rect.Max))};

  int sum = 0;
  int sum_abs = 0;

  for (size_t i = 0; i < 4; ++i) {
    sum += corner_signs[i];
    sum_abs += abs(corner_signs[i]);
  }

  // At least one corner of rectangle lies on a different side of line segment
  return abs(sum) != sum_abs;
}

inline bool RectangleOverlapsBezier(const ImRect& rectangle, const CubicBezier& cubic_bezier) {
  ImVec2 current =
      EvalCubicBezier(0.F, cubic_bezier.P0, cubic_bezier.P1, cubic_bezier.P2, cubic_bezier.P3);
  const float dt = 1.0F / static_cast<float>(cubic_bezier.NumSegments);
  for (int s = 0; s < cubic_bezier.NumSegments; ++s) {
    const ImVec2 next = EvalCubicBezier(static_cast<float>(s + 1) * dt,
        cubic_bezier.P0,
        cubic_bezier.P1,
        cubic_bezier.P2,
        cubic_bezier.P3);
    if (RectangleOverlapsLineSegment(rectangle, current, next)) {
      return true;
    }
    current = next;
  }
  return false;
}

inline bool RectangleOverlapsLink(const ImRect& rectangle,
    const ImVec2& start,
    const ImVec2& end,
    const ImNodesAttributeType start_type) {
  // First level: simple rejection test via rectangle overlap:

  ImRect lrect = ImRect(start, end);
  if (lrect.Min.x > lrect.Max.x) {
    ImSwap(lrect.Min.x, lrect.Max.x);
  }

  if (lrect.Min.y > lrect.Max.y) {
    ImSwap(lrect.Min.y, lrect.Max.y);
  }

  if (rectangle.Overlaps(lrect)) {
    // First, check if either one or both endpoints are trivially contained
    // in the rectangle

    if (rectangle.Contains(start) || rectangle.Contains(end)) {
      return true;
    }

    // Second level of refinement: do a more expensive test against the
    // link

    const CubicBezier cubic_bezier =
        GetCubicBezier(start, end, start_type, GImNodes->Style.LinkLineSegmentsPerLength);
    return RectangleOverlapsBezier(rectangle, cubic_bezier);
  }

  return false;
}

// [SECTION] coordinate space conversion helpers

inline ImVec2 ScreenSpaceToGridSpace(const ImNodesEditorContext& editor, const ImVec2& v) {
  return v - GImNodes->CanvasOriginScreenSpace - editor.Panning;
}

inline ImRect ScreenSpaceToGridSpace(const ImNodesEditorContext& editor, const ImRect& r) {
  return ImRect(ScreenSpaceToGridSpace(editor, r.Min), ScreenSpaceToGridSpace(editor, r.Max));
}

inline ImVec2 GridSpaceToScreenSpace(const ImNodesEditorContext& editor, const ImVec2& v) {
  return v + GImNodes->CanvasOriginScreenSpace + editor.Panning;
}

inline ImVec2 GridSpaceToEditorSpace(const ImNodesEditorContext& editor, const ImVec2& v) {
  return v + editor.Panning;
}

inline ImVec2 EditorSpaceToGridSpace(const ImNodesEditorContext& editor, const ImVec2& v) {
  return v - editor.Panning;
}

inline ImVec2 EditorSpaceToScreenSpace(const ImVec2& v) {
  return GImNodes->CanvasOriginScreenSpace + v;
}

inline ImVec2 MiniMapSpaceToGridSpace(const ImNodesEditorContext& editor, const ImVec2& v) {
  return (v - editor.MiniMapContentScreenSpace.Min) / editor.MiniMapScaling +
         editor.GridContentBounds.Min;
}

inline ImVec2 ScreenSpaceToMiniMapSpace(const ImNodesEditorContext& editor, const ImVec2& v) {
  return (ScreenSpaceToGridSpace(editor, v) - editor.GridContentBounds.Min) *
             editor.MiniMapScaling +
         editor.MiniMapContentScreenSpace.Min;
}

inline ImRect ScreenSpaceToMiniMapSpace(const ImNodesEditorContext& editor, const ImRect& r) {
  return {ScreenSpaceToMiniMapSpace(editor, r.Min), ScreenSpaceToMiniMapSpace(editor, r.Max)};
}

// [SECTION] draw list helper

void ImDrawListGrowChannels(ImDrawList* draw_list, const int num_channels) {
  ImDrawListSplitter& splitter = draw_list->_Splitter;

  if (splitter._Count == 1) {
    splitter.Split(draw_list, num_channels + 1);
    return;
  }

  // NOTE: this logic has been lifted from ImDrawListSplitter::Split with slight modifications
  // to allow nested splits. The main modification is that we only create new ImDrawChannel
  // instances after splitter._Count, instead of over the whole splitter._Channels array like
  // the regular ImDrawListSplitter::Split method does.

  const int old_channel_capacity = splitter._Channels.Size;
  // NOTE: _Channels is not resized down, and therefore _Count <= _Channels.size()!
  const int old_channel_count = splitter._Count;
  const int requested_channel_count = old_channel_count + num_channels;
  if (old_channel_capacity < old_channel_count + num_channels) {
    splitter._Channels.resize(requested_channel_count);
  }

  splitter._Count = requested_channel_count;

  for (int i = old_channel_count; i < requested_channel_count; ++i) {
    ImDrawChannel& channel = splitter._Channels[i];

    // If we're inside the old capacity region of the array, we need to reuse the existing
    // memory of the command and index buffers.
    if (i < old_channel_capacity) {
      channel._CmdBuffer.resize(0);
      channel._IdxBuffer.resize(0);
    }
    // Else, we need to construct new draw channels.
    else {
      IM_PLACEMENT_NEW(&channel) ImDrawChannel();
    }

    {
      ImDrawCmd draw_cmd;
      draw_cmd.ClipRect = draw_list->_ClipRectStack.back();
      draw_cmd.TextureId = draw_list->_TextureIdStack.back();
      channel._CmdBuffer.push_back(draw_cmd);
    }
  }
}

void ImDrawListSplitterSwapChannels(
    ImDrawListSplitter& splitter, const int lhs_idx, const int rhs_idx) {
  if (lhs_idx == rhs_idx) {
    return;
  }

  IM_ASSERT(lhs_idx >= 0 && lhs_idx < splitter._Count);
  IM_ASSERT(rhs_idx >= 0 && rhs_idx < splitter._Count);

  ImDrawChannel& lhs_channel = splitter._Channels[lhs_idx];
  ImDrawChannel& rhs_channel = splitter._Channels[rhs_idx];
  lhs_channel._CmdBuffer.swap(rhs_channel._CmdBuffer);
  lhs_channel._IdxBuffer.swap(rhs_channel._IdxBuffer);

  const int current_channel = splitter._Current;

  if (current_channel == lhs_idx) {
    splitter._Current = rhs_idx;
  } else if (current_channel == rhs_idx) {
    splitter._Current = lhs_idx;
  }
}

void DrawListSet(ImDrawList* window_draw_list) {
  GImNodes->CanvasDrawList = window_draw_list;
  GImNodes->NodeIdxToSubmissionIdx.Clear();
  GImNodes->NodeIdxSubmissionOrder.clear();
}

// The draw list channels are structured as follows. First we have our base channel, the canvas grid
// on which we render the grid lines in BeginNodeEditor(). The base channel is the reason
// draw_list_submission_idx_to_background_channel_idx offsets the index by one. Each BeginNode()
// call appends two new draw channels, for the node background and foreground. The node foreground
// is the channel into which the node's ImGui content is rendered. Finally, in EndNodeEditor() we
// append one last draw channel for rendering the selection box and the incomplete link on top of
// everything else.
//
// +----------+----------+----------+----------+----------+----------+
// |          |          |          |          |          |          |
// |canvas    |node      |node      |...       |...       |click     |
// |grid      |background|foreground|          |          |interaction
// |          |          |          |          |          |          |
// +----------+----------+----------+----------+----------+----------+
//            |                     |
//            |   submission idx    |
//            |                     |
//            -----------------------

void DrawListAddNode(const int node_idx) {
  GImNodes->NodeIdxToSubmissionIdx.SetInt(
      static_cast<ImGuiID>(node_idx), GImNodes->NodeIdxSubmissionOrder.Size);
  GImNodes->NodeIdxSubmissionOrder.push_back(node_idx);
  ImDrawListGrowChannels(GImNodes->CanvasDrawList, 2);
}

void DrawListAppendClickInteractionChannel() {
  // NOTE: don't use this function outside EndNodeEditor. Using this before all nodes have been
  // added will screw up the node draw order.
  ImDrawListGrowChannels(GImNodes->CanvasDrawList, 1);
}

int DrawListSubmissionIdxToBackgroundChannelIdx(const int submission_idx) {
  // NOTE: the first channel is the canvas background, i.e. the grid
  return 1 + 2 * submission_idx;
}

int DrawListSubmissionIdxToForegroundChannelIdx(const int submission_idx) {
  return DrawListSubmissionIdxToBackgroundChannelIdx(submission_idx) + 1;
}

void DrawListActivateClickInteractionChannel() {
  GImNodes->CanvasDrawList->_Splitter.SetCurrentChannel(
      GImNodes->CanvasDrawList, GImNodes->CanvasDrawList->_Splitter._Count - 1);
}

void DrawListActivateCurrentNodeForeground() {
  const int foreground_channel_idx =
      DrawListSubmissionIdxToForegroundChannelIdx(GImNodes->NodeIdxSubmissionOrder.Size - 1);
  GImNodes->CanvasDrawList->_Splitter.SetCurrentChannel(
      GImNodes->CanvasDrawList, foreground_channel_idx);
}

void DrawListActivateNodeBackground(const int node_idx) {
  const int submission_idx =
      GImNodes->NodeIdxToSubmissionIdx.GetInt(static_cast<ImGuiID>(node_idx), -1);
  // There is a discrepancy in the submitted node count and the rendered node count! Did you call
  // one of the following functions
  // * EditorContextMoveToNode
  // * SetNodeScreenSpacePos
  // * SetNodeGridSpacePos
  // * SetNodeDraggable
  // after the BeginNode/EndNode function calls?
  IM_ASSERT(submission_idx != -1);
  const int background_channel_idx = DrawListSubmissionIdxToBackgroundChannelIdx(submission_idx);
  GImNodes->CanvasDrawList->_Splitter.SetCurrentChannel(
      GImNodes->CanvasDrawList, background_channel_idx);
}

void DrawListSwapSubmissionIndices(const int lhs_idx, const int rhs_idx) {
  IM_ASSERT(lhs_idx != rhs_idx);

  const int lhs_foreground_channel_idx = DrawListSubmissionIdxToForegroundChannelIdx(lhs_idx);
  const int lhs_background_channel_idx = DrawListSubmissionIdxToBackgroundChannelIdx(lhs_idx);
  const int rhs_foreground_channel_idx = DrawListSubmissionIdxToForegroundChannelIdx(rhs_idx);
  const int rhs_background_channel_idx = DrawListSubmissionIdxToBackgroundChannelIdx(rhs_idx);

  ImDrawListSplitterSwapChannels(
      GImNodes->CanvasDrawList->_Splitter, lhs_background_channel_idx, rhs_background_channel_idx);
  ImDrawListSplitterSwapChannels(
      GImNodes->CanvasDrawList->_Splitter, lhs_foreground_channel_idx, rhs_foreground_channel_idx);
}

void DrawListSortChannelsByDepth(const ImVector<int>& node_idx_depth_order) {
  if (GImNodes->NodeIdxToSubmissionIdx.Data.Size < 2) {
    return;
  }

  IM_ASSERT(node_idx_depth_order.Size == GImNodes->NodeIdxSubmissionOrder.Size);

  int start_idx = node_idx_depth_order.Size - 1;

  while (node_idx_depth_order[start_idx] == GImNodes->NodeIdxSubmissionOrder[start_idx]) {
    if (--start_idx == 0) {
      // early out if submission order and depth order are the same
      return;
    }
  }

  // TODO: this is an O(N^2) algorithm. It might be worthwhile revisiting this to see if the time
  // complexity can be reduced.

  for (int depth_idx = start_idx; depth_idx > 0; --depth_idx) {
    const int node_idx = node_idx_depth_order[depth_idx];

    // Find the current index of the node_idx in the submission order array
    int submission_idx = -1;
    for (int i = 0; i < GImNodes->NodeIdxSubmissionOrder.Size; ++i) {
      if (GImNodes->NodeIdxSubmissionOrder[i] == node_idx) {
        submission_idx = i;
        break;
      }
    }
    IM_ASSERT(submission_idx >= 0);

    if (submission_idx == depth_idx) {
      continue;
    }

    for (int j = submission_idx; j < depth_idx; ++j) {
      DrawListSwapSubmissionIndices(j, j + 1);
      ImSwap(GImNodes->NodeIdxSubmissionOrder[j], GImNodes->NodeIdxSubmissionOrder[j + 1]);
    }
  }
}

// [SECTION] ui state logic

ImVec2 GetScreenSpacePinCoordinates(
    const ImRect& node_rect, const ImRect& attribute_rect, const ImNodesAttributeType type) {
  IM_ASSERT(type == ImNodesAttributeType_Input || type == ImNodesAttributeType_Output);
  const float x = type == ImNodesAttributeType_Input
                      ? (node_rect.Min.x - GImNodes->Style.PinOffset)
                      : (node_rect.Max.x + GImNodes->Style.PinOffset);
  return {x, 0.5F * (attribute_rect.Min.y + attribute_rect.Max.y)};
}

ImVec2 GetScreenSpacePinCoordinates(const ImNodesEditorContext& editor, const ImPinData& pin) {
  const ImRect& parent_node_rect = editor.Nodes.Pool[pin.ParentNodeIdx].Rect;
  return GetScreenSpacePinCoordinates(parent_node_rect, pin.AttributeRect, pin.Type);
}

bool MouseInCanvas() {
  // This flag should be true either when hovering or clicking something in the canvas.
  const bool is_window_hovered_or_focused = ImGui::IsWindowHovered() || ImGui::IsWindowFocused();

  return is_window_hovered_or_focused &&
         GImNodes->CanvasRectScreenSpace.Contains(ImGui::GetMousePos());
}

void BeginNodeSelection(ImNodesEditorContext& editor, const int node_idx) {
  // Don't start selecting a node if we are e.g. already creating and dragging
  // a new link! New link creation can happen when the mouse is clicked over
  // a node, but within the hover radius of a pin.
  if (editor.ClickInteraction.Type != ImNodesClickInteractionType_None) {
    return;
  }

  editor.ClickInteraction.Type = ImNodesClickInteractionType_Node;
  // If the node is not already contained in the selection, then we want only
  // the interaction node to be selected, effective immediately.
  //
  // If the multiple selection modifier is active, we want to add this node
  // to the current list of selected nodes.
  //
  // Otherwise, we want to allow for the possibility of multiple nodes to be
  // moved at once.
  if (!editor.SelectedNodeIndices.contains(node_idx)) {
    editor.SelectedLinkIndices.clear();
    if (!GImNodes->MultipleSelectModifier) {
      editor.SelectedNodeIndices.clear();
    }
    editor.SelectedNodeIndices.push_back(node_idx);

    // Ensure that individually selected nodes get rendered on top
    ImVector<int>& depth_stack = editor.NodeDepthOrder;
    const int* const elem = depth_stack.find(node_idx);
    IM_ASSERT(elem != depth_stack.end());
    depth_stack.erase(elem);
    depth_stack.push_back(node_idx);
  }
  // Deselect a previously-selected node
  else if (GImNodes->MultipleSelectModifier) {
    const int* const node_ptr = editor.SelectedNodeIndices.find(node_idx);
    editor.SelectedNodeIndices.erase(node_ptr);

    // Don't allow dragging after deselecting
    editor.ClickInteraction.Type = ImNodesClickInteractionType_None;
  }

  // To support snapping of multiple nodes, we need to store the offset of
  // each node in the selection to the origin of the dragged node.
  const ImVec2 ref_origin = editor.Nodes.Pool[node_idx].Origin;
  editor.PrimaryNodeOffset =
      ref_origin + GImNodes->CanvasOriginScreenSpace + editor.Panning - GImNodes->MousePos;

  editor.SelectedNodeOffsets.clear();
  for (int idx = 0; idx < editor.SelectedNodeIndices.Size; idx++) {
    const int node = editor.SelectedNodeIndices[idx];
    const ImVec2 node_origin = editor.Nodes.Pool[node].Origin - ref_origin;
    editor.SelectedNodeOffsets.push_back(node_origin);
  }
}

void BeginLinkSelection(ImNodesEditorContext& editor, const int link_idx) {
  editor.ClickInteraction.Type = ImNodesClickInteractionType_Link;
  // When a link is selected, clear all other selections, and insert the link
  // as the sole selection.
  editor.SelectedNodeIndices.clear();
  editor.SelectedLinkIndices.clear();
  editor.SelectedLinkIndices.push_back(link_idx);
}

void BeginLinkDetach(ImNodesEditorContext& editor, const int link_idx, const int detach_pin_idx) {
  const ImLinkData& link = editor.Links.Pool[link_idx];
  ImClickInteractionState& state = editor.ClickInteraction;
  state.Type = ImNodesClickInteractionType_LinkCreation;
  state.LinkCreation.EndPinIdx.Reset();
  state.LinkCreation.StartPinIdx =
      detach_pin_idx == link.StartPinIdx ? link.EndPinIdx : link.StartPinIdx;
  GImNodes->DeletedLinkIdx = link_idx;
}

void BeginLinkCreation(ImNodesEditorContext& editor, const int hovered_pin_idx) {
  editor.ClickInteraction.Type = ImNodesClickInteractionType_LinkCreation;
  editor.ClickInteraction.LinkCreation.StartPinIdx = hovered_pin_idx;
  editor.ClickInteraction.LinkCreation.EndPinIdx.Reset();
  editor.ClickInteraction.LinkCreation.Type = ImNodesLinkCreationType_Standard;
  GImNodes->ImNodesUIState |= ImNodesUIState_LinkStarted;
}

void BeginLinkInteraction(ImNodesEditorContext& editor,
    const int link_idx,
    const ImOptionalIndex pin_idx = ImOptionalIndex()) {
  // Check if we are clicking the link with the modifier pressed.
  // This will in a link detach via clicking.
  const bool modifier_pressed = GImNodes->Io.LinkDetachWithModifierClick.Modifier != nullptr &&
                                *GImNodes->Io.LinkDetachWithModifierClick.Modifier;

  if (modifier_pressed) {
    const ImLinkData& link = editor.Links.Pool[link_idx];
    const ImPinData& start_pin = editor.Pins.Pool[link.StartPinIdx];
    const ImPinData& end_pin = editor.Pins.Pool[link.EndPinIdx];
    const ImVec2& mouse_pos = GImNodes->MousePos;
    const float dist_to_start = ImLengthSqr(start_pin.Pos - mouse_pos);
    const float dist_to_end = ImLengthSqr(end_pin.Pos - mouse_pos);
    const int closest_pin_idx = dist_to_start < dist_to_end ? link.StartPinIdx : link.EndPinIdx;

    editor.ClickInteraction.Type = ImNodesClickInteractionType_LinkCreation;
    BeginLinkDetach(editor, link_idx, closest_pin_idx);
    editor.ClickInteraction.LinkCreation.Type = ImNodesLinkCreationType_FromDetach;
  } else {
    if (pin_idx.HasValue()) {
      const int hovered_pin_flags = editor.Pins.Pool[pin_idx.Value()].Flags;

      // Check the 'click and drag to detach' case.
      if ((hovered_pin_flags & ImNodesAttributeFlags_EnableLinkDetachWithDragClick) != 0) {
        BeginLinkDetach(editor, link_idx, pin_idx.Value());
        editor.ClickInteraction.LinkCreation.Type = ImNodesLinkCreationType_FromDetach;
      } else {
        BeginLinkCreation(editor, pin_idx.Value());
      }
    } else {
      BeginLinkSelection(editor, link_idx);
    }
  }
}

static inline bool IsMiniMapHovered();

void BeginCanvasInteraction(ImNodesEditorContext& editor) {
  const bool any_ui_element_hovered =
      GImNodes->HoveredNodeIdx.HasValue() || GImNodes->HoveredLinkIdx.HasValue() ||
      GImNodes->HoveredPinIdx.HasValue() || ImGui::IsAnyItemHovered();

  const bool mouse_not_in_canvas = !MouseInCanvas();

  if (editor.ClickInteraction.Type != ImNodesClickInteractionType_None || any_ui_element_hovered ||
      mouse_not_in_canvas) {
    return;
  }

  const bool started_panning = GImNodes->AltMouseClicked;

  if (started_panning) {
    editor.ClickInteraction.Type = ImNodesClickInteractionType_Panning;
  } else if (GImNodes->LeftMouseClicked) {
    editor.ClickInteraction.Type = ImNodesClickInteractionType_BoxSelection;
    editor.ClickInteraction.BoxSelector.Rect.Min =
        ScreenSpaceToGridSpace(editor, GImNodes->MousePos);
  }
}

void BoxSelectorUpdateSelection(ImNodesEditorContext& editor, ImRect box_rect) {
  // Invert box selector coordinates as needed

  if (box_rect.Min.x > box_rect.Max.x) {
    ImSwap(box_rect.Min.x, box_rect.Max.x);
  }

  if (box_rect.Min.y > box_rect.Max.y) {
    ImSwap(box_rect.Min.y, box_rect.Max.y);
  }

  // Update node selection

  editor.SelectedNodeIndices.clear();

  // Test for overlap against node rectangles

  for (int node_idx = 0; node_idx < editor.Nodes.Pool.size(); ++node_idx) {
    if (editor.Nodes.InUse[node_idx]) {
      const ImNodeData& node = editor.Nodes.Pool[node_idx];
      if (box_rect.Overlaps(node.Rect)) {
        editor.SelectedNodeIndices.push_back(node_idx);
      }
    }
  }

  // Update link selection

  editor.SelectedLinkIndices.clear();

  // Test for overlap against links

  for (int link_idx = 0; link_idx < editor.Links.Pool.size(); ++link_idx) {
    if (editor.Links.InUse[link_idx]) {
      const ImLinkData& link = editor.Links.Pool[link_idx];

      const ImPinData& pin_start = editor.Pins.Pool[link.StartPinIdx];
      const ImPinData& pin_end = editor.Pins.Pool[link.EndPinIdx];
      const ImRect& node_start_rect = editor.Nodes.Pool[pin_start.ParentNodeIdx].Rect;
      const ImRect& node_end_rect = editor.Nodes.Pool[pin_end.ParentNodeIdx].Rect;

      const ImVec2 start =
          GetScreenSpacePinCoordinates(node_start_rect, pin_start.AttributeRect, pin_start.Type);
      const ImVec2 end =
          GetScreenSpacePinCoordinates(node_end_rect, pin_end.AttributeRect, pin_end.Type);

      // Test
      if (RectangleOverlapsLink(box_rect, start, end, pin_start.Type)) {
        editor.SelectedLinkIndices.push_back(link_idx);
      }
    }
  }
}

ImVec2 SnapOriginToGrid(ImVec2 origin) {
  if ((GImNodes->Style.Flags & ImNodesStyleFlags_GridSnapping) != 0) {
    const float spacing = GImNodes->Style.GridSpacing;
    const float spacing2 = spacing * 0.5F;

    // Snap the origin to the nearest grid point in any direction
    const float modx = fmodf(fabsf(origin.x) + spacing2, spacing) - spacing2;
    const float mody = fmodf(fabsf(origin.y) + spacing2, spacing) - spacing2;
    origin.x += (origin.x < 0.F) ? modx : -modx;
    origin.y += (origin.y < 0.F) ? mody : -mody;
  }

  return origin;
}

void TranslateSelectedNodes(ImNodesEditorContext& editor) {
  if (GImNodes->LeftMouseDragging) {
    // If we have grid snap enabled, don't start moving nodes until we've moved the mouse
    // slightly
    const bool should_translate = (GImNodes->Style.Flags & ImNodesStyleFlags_GridSnapping) == 0 ||
                                  ImGui::GetIO().MouseDragMaxDistanceSqr[0] > 5.0;

    const ImVec2 origin = SnapOriginToGrid(GImNodes->MousePos - GImNodes->CanvasOriginScreenSpace -
                                           editor.Panning + editor.PrimaryNodeOffset);
    for (int i = 0; i < editor.SelectedNodeIndices.size(); ++i) {
      const ImVec2 node_rel = editor.SelectedNodeOffsets[i];
      const int node_idx = editor.SelectedNodeIndices[i];
      ImNodeData& node = editor.Nodes.Pool[node_idx];
      if (node.Draggable && should_translate) {
        node.Origin = origin + node_rel + editor.AutoPanningDelta;
      }
    }
  }
}

struct LinkPredicate {
  bool operator()(const ImLinkData& lhs, const ImLinkData& rhs) const {
    // Do a unique compare by sorting the pins' addresses.
    // This catches duplicate links, whether they are in the
    // same direction or not.
    // Sorting by pin index should have the uniqueness guarantees as sorting
    // by id -- each unique id will get one slot in the link pool array.

    int lhs_start = lhs.StartPinIdx;
    int lhs_end = lhs.EndPinIdx;
    int rhs_start = rhs.StartPinIdx;
    int rhs_end = rhs.EndPinIdx;

    if (lhs_start > lhs_end) {
      ImSwap(lhs_start, lhs_end);
    }

    if (rhs_start > rhs_end) {
      ImSwap(rhs_start, rhs_end);
    }

    return lhs_start == rhs_start && lhs_end == rhs_end;
  }
};

ImOptionalIndex FindDuplicateLink(
    const ImNodesEditorContext& editor, const int start_pin_idx, const int end_pin_idx) {
  ImLinkData test_link(0);
  test_link.StartPinIdx = start_pin_idx;
  test_link.EndPinIdx = end_pin_idx;
  for (int link_idx = 0; link_idx < editor.Links.Pool.size(); ++link_idx) {
    const ImLinkData& link = editor.Links.Pool[link_idx];
    if (LinkPredicate()(test_link, link) && editor.Links.InUse[link_idx]) {
      return {link_idx};
    }
  }

  return {};
}

bool ShouldLinkSnapToPin(const ImNodesEditorContext& editor,
    const ImPinData& start_pin,
    const int hovered_pin_idx,
    const ImOptionalIndex duplicate_link) {
  const ImPinData& end_pin = editor.Pins.Pool[hovered_pin_idx];

  // The end pin must be in a different node
  if (start_pin.ParentNodeIdx == end_pin.ParentNodeIdx) {
    return false;
  }

  // The end pin must be of a different type
  if (start_pin.Type == end_pin.Type) {
    return false;
  }

  // The link to be created must not be a duplicate, unless it is the link which was created on
  // snap. In that case we want to snap, since we want it to appear visually as if the created
  // link remains snapped to the pin.
  if (duplicate_link.HasValue() && !(duplicate_link == GImNodes->SnapLinkIdx)) {
    return false;
  }

  return true;
}

void ClickInteractionUpdate(ImNodesEditorContext& editor) {
  switch (editor.ClickInteraction.Type) {
    case ImNodesClickInteractionType_BoxSelection: {
      editor.ClickInteraction.BoxSelector.Rect.Max =
          ScreenSpaceToGridSpace(editor, GImNodes->MousePos);

      ImRect box_rect = editor.ClickInteraction.BoxSelector.Rect;
      box_rect.Min = GridSpaceToScreenSpace(editor, box_rect.Min);
      box_rect.Max = GridSpaceToScreenSpace(editor, box_rect.Max);

      BoxSelectorUpdateSelection(editor, box_rect);

      const ImU32 box_selector_color = GImNodes->Style.Colors[ImNodesCol_BoxSelector];
      const ImU32 box_selector_outline = GImNodes->Style.Colors[ImNodesCol_BoxSelectorOutline];
      GImNodes->CanvasDrawList->AddRectFilled(box_rect.Min, box_rect.Max, box_selector_color);
      GImNodes->CanvasDrawList->AddRect(box_rect.Min, box_rect.Max, box_selector_outline);

      if (GImNodes->LeftMouseReleased) {
        ImVector<int>& depth_stack = editor.NodeDepthOrder;
        const ImVector<int>& selected_idxs = editor.SelectedNodeIndices;

        // Bump the selected node indices, in order, to the top of the depth stack.
        // NOTE: this algorithm has worst case time complexity of O(N^2), if the node selection
        // is ~ N (due to selected_idxs.contains()).

        if ((selected_idxs.Size > 0) && (selected_idxs.Size < depth_stack.Size)) {
          int num_moved = 0;  // The number of indices moved. Stop after selected_idxs.Size
          for (int i = 0; i < depth_stack.Size - selected_idxs.Size; ++i) {
            for (int node_idx = depth_stack[i]; selected_idxs.contains(node_idx);
                 node_idx = depth_stack[i]) {
              depth_stack.erase(depth_stack.begin() + static_cast<size_t>(i));
              depth_stack.push_back(node_idx);
              ++num_moved;
            }

            if (num_moved == selected_idxs.Size) {
              break;
            }
          }
        }

        editor.ClickInteraction.Type = ImNodesClickInteractionType_None;
      }
    } break;
    case ImNodesClickInteractionType_Node: {
      TranslateSelectedNodes(editor);

      if (GImNodes->LeftMouseReleased) {
        editor.ClickInteraction.Type = ImNodesClickInteractionType_None;
      }
    } break;
    case ImNodesClickInteractionType_Link: {
      if (GImNodes->LeftMouseReleased) {
        editor.ClickInteraction.Type = ImNodesClickInteractionType_None;
      }
    } break;
    case ImNodesClickInteractionType_LinkCreation: {
      const ImPinData& start_pin =
          editor.Pins.Pool[editor.ClickInteraction.LinkCreation.StartPinIdx];

      const ImOptionalIndex maybe_duplicate_link_idx =
          GImNodes->HoveredPinIdx.HasValue() ? FindDuplicateLink(editor,
                                                   editor.ClickInteraction.LinkCreation.StartPinIdx,
                                                   GImNodes->HoveredPinIdx.Value())
                                             : ImOptionalIndex();

      const bool should_snap =
          GImNodes->HoveredPinIdx.HasValue() &&
          ShouldLinkSnapToPin(
              editor, start_pin, GImNodes->HoveredPinIdx.Value(), maybe_duplicate_link_idx);

      // If we created on snap and the hovered pin is empty or changed, then we need signal that
      // the link's state has changed.
      const bool snapping_pin_changed =
          editor.ClickInteraction.LinkCreation.EndPinIdx.HasValue() &&
          !(GImNodes->HoveredPinIdx == editor.ClickInteraction.LinkCreation.EndPinIdx);

      // Detach the link that was created by this link event if it's no longer in snap range
      if (snapping_pin_changed && GImNodes->SnapLinkIdx.HasValue()) {
        BeginLinkDetach(editor,
            GImNodes->SnapLinkIdx.Value(),
            editor.ClickInteraction.LinkCreation.EndPinIdx.Value());
      }

      const ImVec2 start_pos = GetScreenSpacePinCoordinates(editor, start_pin);
      // If we are within the hover radius of a receiving pin, snap the link
      // endpoint to it
      const ImVec2 end_pos = should_snap ? GetScreenSpacePinCoordinates(editor,
                                               editor.Pins.Pool[GImNodes->HoveredPinIdx.Value()])
                                         : GImNodes->MousePos;

      const CubicBezier cubic_bezier = GetCubicBezier(
          start_pos, end_pos, start_pin.Type, GImNodes->Style.LinkLineSegmentsPerLength);
      GImNodes->CanvasDrawList->AddBezierCubic(cubic_bezier.P0,
          cubic_bezier.P1,
          cubic_bezier.P2,
          cubic_bezier.P3,
          GImNodes->Style.Colors[ImNodesCol_Link],
          GImNodes->Style.LinkThickness,
          cubic_bezier.NumSegments);

      const bool link_creation_on_snap = GImNodes->HoveredPinIdx.HasValue() &&
                                         ((editor.Pins.Pool[GImNodes->HoveredPinIdx.Value()].Flags &
                                              ImNodesAttributeFlags_EnableLinkCreationOnSnap) != 0);

      if (!should_snap) {
        editor.ClickInteraction.LinkCreation.EndPinIdx.Reset();
      }

      const bool create_link =
          should_snap && (GImNodes->LeftMouseReleased || link_creation_on_snap);

      if (create_link && !maybe_duplicate_link_idx.HasValue()) {
        // Avoid send OnLinkCreated() events every frame if the snap link is not saved
        // (only applies for EnableLinkCreationOnSnap)
        if (!GImNodes->LeftMouseReleased &&
            editor.ClickInteraction.LinkCreation.EndPinIdx == GImNodes->HoveredPinIdx) {
          break;
        }

        GImNodes->ImNodesUIState |= ImNodesUIState_LinkCreated;
        editor.ClickInteraction.LinkCreation.EndPinIdx = GImNodes->HoveredPinIdx.Value();
      }

      if (GImNodes->LeftMouseReleased) {
        editor.ClickInteraction.Type = ImNodesClickInteractionType_None;
        if (!create_link) {
          GImNodes->ImNodesUIState |= ImNodesUIState_LinkDropped;
        }
      }
    } break;
    case ImNodesClickInteractionType_Panning: {
      const bool dragging = GImNodes->AltMouseDragging;

      if (dragging) {
        editor.Panning += ImGui::GetIO().MouseDelta;
      } else {
        editor.ClickInteraction.Type = ImNodesClickInteractionType_None;
      }
    } break;
    case ImNodesClickInteractionType_ImGuiItem: {
      if (GImNodes->LeftMouseReleased) {
        editor.ClickInteraction.Type = ImNodesClickInteractionType_None;
      }
    }
    case ImNodesClickInteractionType_None:
      break;
    default:
      IM_ASSERT(!"Unreachable code!");
      break;
  }
}

void ResolveOccludedPins(const ImNodesEditorContext& editor, ImVector<int>& occluded_pin_indices) {
  const ImVector<int>& depth_stack = editor.NodeDepthOrder;

  occluded_pin_indices.resize(0);

  if (depth_stack.Size < 2) {
    return;
  }

  // For each node in the depth stack
  for (int depth_idx = 0; depth_idx < (depth_stack.Size - 1); ++depth_idx) {
    const ImNodeData& node_below = editor.Nodes.Pool[depth_stack[depth_idx]];

    // Iterate over the rest of the depth stack to find nodes overlapping the pins
    for (int next_depth_idx = depth_idx + 1; next_depth_idx < depth_stack.Size; ++next_depth_idx) {
      const ImRect& rect_above = editor.Nodes.Pool[depth_stack[next_depth_idx]].Rect;

      // Iterate over each pin
      for (int idx = 0; idx < node_below.PinIndices.Size; ++idx) {
        const int pin_idx = node_below.PinIndices[idx];
        const ImVec2& pin_pos = editor.Pins.Pool[pin_idx].Pos;

        if (rect_above.Contains(pin_pos)) {
          occluded_pin_indices.push_back(pin_idx);
        }
      }
    }
  }
}

ImOptionalIndex ResolveHoveredPin(
    const ImObjectPool<ImPinData>& pins, const ImVector<int>& occluded_pin_indices) {
  float smallest_distance = FLT_MAX;
  ImOptionalIndex pin_idx_with_smallest_distance;

  const float hover_radius_sqr = GImNodes->Style.PinHoverRadius * GImNodes->Style.PinHoverRadius;

  for (int idx = 0; idx < pins.Pool.Size; ++idx) {
    if (!pins.InUse[idx]) {
      continue;
    }

    if (occluded_pin_indices.contains(idx)) {
      continue;
    }

    const ImVec2& pin_pos = pins.Pool[idx].Pos;
    const float distance_sqr = ImLengthSqr(pin_pos - GImNodes->MousePos);

    // TODO: GImNodes->Style.PinHoverRadius needs to be copied into pin data and the pin-local
    // value used here. This is no longer called in BeginAttribute/EndAttribute scope and the
    // detected pin might have a different hover radius than what the user had when calling
    // BeginAttribute/EndAttribute.
    if (distance_sqr < hover_radius_sqr && distance_sqr < smallest_distance) {
      smallest_distance = distance_sqr;
      pin_idx_with_smallest_distance = idx;
    }
  }

  return pin_idx_with_smallest_distance;
}

ImOptionalIndex ResolveHoveredNode(const ImVector<int>& depth_stack) {
  if (GImNodes->NodeIndicesOverlappingWithMouse.empty()) {
    return {};
  }

  if (GImNodes->NodeIndicesOverlappingWithMouse.size() == 1) {
    return {GImNodes->NodeIndicesOverlappingWithMouse[0]};
  }

  int largest_depth_idx = -1;
  int node_idx_on_top = -1;

  for (const int node_idx : GImNodes->NodeIndicesOverlappingWithMouse) {
    for (int depth_idx = 0; depth_idx < depth_stack.size(); ++depth_idx) {
      if (depth_stack[depth_idx] == node_idx && (depth_idx > largest_depth_idx)) {
        largest_depth_idx = depth_idx;
        node_idx_on_top = node_idx;
      }
    }
  }

  IM_ASSERT(node_idx_on_top != -1);
  return {node_idx_on_top};
}

ImOptionalIndex ResolveHoveredLink(
    const ImObjectPool<ImLinkData>& links, const ImObjectPool<ImPinData>& pins) {
  float smallest_distance = FLT_MAX;
  ImOptionalIndex link_idx_with_smallest_distance;

  // There are two ways a link can be detected as "hovered".
  // 1. The link is within hover distance to the mouse. The closest such link is selected as being
  // hovered over.
  // 2. If the link is connected to the currently hovered pin.
  //
  // The latter is a requirement for link detaching with drag click to work, as both a link and
  // pin are required to be hovered over for the feature to work.

  for (int idx = 0; idx < links.Pool.Size; ++idx) {
    if (!links.InUse[idx]) {
      continue;
    }

    const ImLinkData& link = links.Pool[idx];
    const ImPinData& start_pin = pins.Pool[link.StartPinIdx];
    const ImPinData& end_pin = pins.Pool[link.EndPinIdx];

    // If there is a hovered pin links can only be considered hovered if they use that pin
    if (GImNodes->HoveredPinIdx.HasValue()) {
      if (GImNodes->HoveredPinIdx == link.StartPinIdx ||
          GImNodes->HoveredPinIdx == link.EndPinIdx) {
        return idx;
      }
      continue;
    }

    // TODO: the calculated CubicBeziers could be cached since we generate them again when
    // rendering the links

    const CubicBezier cubic_bezier = GetCubicBezier(
        start_pin.Pos, end_pin.Pos, start_pin.Type, GImNodes->Style.LinkLineSegmentsPerLength);

    // The distance test
    {
      const ImRect link_rect = GetContainingRectForCubicBezier(cubic_bezier);

      // First, do a simple bounding box test against the box containing the link
      // to see whether calculating the distance to the link is worth doing.
      if (link_rect.Contains(GImNodes->MousePos)) {
        const float distance =
            GetDistanceToCubicBezier(GImNodes->MousePos, cubic_bezier, cubic_bezier.NumSegments);

        // TODO: GImNodes->Style.LinkHoverDistance could be also copied into ImLinkData,
        // since we're not calling this function in the same scope as ImNodes::Link(). The
        // rendered/detected link might have a different hover distance than what the user
        // had specified when calling Link()
        if (distance < GImNodes->Style.LinkHoverDistance && distance < smallest_distance) {
          smallest_distance = distance;
          link_idx_with_smallest_distance = idx;
        }
      }
    }
  }

  return link_idx_with_smallest_distance;
}

// [SECTION] render helpers

inline ImRect GetItemRect() {
  return {ImGui::GetItemRectMin(), ImGui::GetItemRectMax()};
}

inline ImVec2 GetNodeTitleBarOrigin(const ImNodeData& node) {
  return node.Origin + node.LayoutStyle.Padding;
}

inline ImVec2 GetNodeContentOrigin(const ImNodeData& node) {
  const ImVec2 title_bar_height = {
      0.F, node.TitleBarContentRect.GetHeight() + 2.0F * node.LayoutStyle.Padding.y};
  return node.Origin + title_bar_height + node.LayoutStyle.Padding;
}

inline ImRect GetNodeTitleRect(const ImNodeData& node) {
  ImRect expanded_title_rect = node.TitleBarContentRect;
  expanded_title_rect.Expand(node.LayoutStyle.Padding);

  return {expanded_title_rect.Min,
      expanded_title_rect.Min + ImVec2(node.Rect.GetWidth(), 0.F) +
          ImVec2(0.F, expanded_title_rect.GetHeight())};
}

void DrawGrid(ImNodesEditorContext& editor, const ImVec2& canvas_size) {
  const ImVec2 offset = editor.Panning;
  const ImU32 line_color = GImNodes->Style.Colors[ImNodesCol_GridLine];
  const ImU32 line_color_prim = GImNodes->Style.Colors[ImNodesCol_GridLinePrimary];
  const bool draw_primary = (GImNodes->Style.Flags & ImNodesStyleFlags_GridLinesPrimary) != 0;

  for (float x = fmodf(offset.x, GImNodes->Style.GridSpacing); x < canvas_size.x;
       x += GImNodes->Style.GridSpacing) {
    GImNodes->CanvasDrawList->AddLine(EditorSpaceToScreenSpace(ImVec2(x, 0.0F)),
        EditorSpaceToScreenSpace(ImVec2(x, canvas_size.y)),
        offset.x - x == 0.F && draw_primary ? line_color_prim : line_color);
  }

  for (float y = fmodf(offset.y, GImNodes->Style.GridSpacing); y < canvas_size.y;
       y += GImNodes->Style.GridSpacing) {
    GImNodes->CanvasDrawList->AddLine(EditorSpaceToScreenSpace(ImVec2(0.0F, y)),
        EditorSpaceToScreenSpace(ImVec2(canvas_size.x, y)),
        offset.y - y == 0.F && draw_primary ? line_color_prim : line_color);
  }
}

struct QuadOffsets {
  ImVec2 TopLeft, BottomLeft, BottomRight, TopRight;
};

QuadOffsets CalculateQuadOffsets(const float side_length) {
  const float half_side = 0.5F * side_length;

  QuadOffsets offset;

  offset.TopLeft = ImVec2(-half_side, half_side);
  offset.BottomLeft = ImVec2(-half_side, -half_side);
  offset.BottomRight = ImVec2(half_side, -half_side);
  offset.TopRight = ImVec2(half_side, half_side);

  return offset;
}

struct TriangleOffsets {
  ImVec2 TopLeft, BottomLeft, Right;
};

TriangleOffsets CalculateTriangleOffsets(const float side_length) {
  // Calculates the Vec2 offsets from an equilateral triangle's midpoint to
  // its vertices. Here is how the left_offset and right_offset are
  // calculated.
  //
  // For an equilateral triangle of side length s, the
  // triangle's height, h, is h = s * sqrt(3) / 2.
  //
  // The length from the base to the midpoint is (1 / 3) * h. The length from
  // the midpoint to the triangle vertex is (2 / 3) * h.
  const float sqrt_3 = sqrtf(3.0F);
  const float left_offset = -0.1666666666667F * sqrt_3 * side_length;
  const float right_offset = 0.333333333333F * sqrt_3 * side_length;
  const float vertical_offset = 0.5F * side_length;

  TriangleOffsets offset;
  offset.TopLeft = ImVec2(left_offset, vertical_offset);
  offset.BottomLeft = ImVec2(left_offset, -vertical_offset);
  offset.Right = ImVec2(right_offset, 0.f);

  return offset;
}

void DrawPinShape(const ImVec2& pin_pos, const ImPinData& pin, const ImU32 pin_color) {
  static const int circle_num_segments = 8;

  switch (pin.Shape) {
    case ImNodesPinShape_Circle: {
      GImNodes->CanvasDrawList->AddCircle(pin_pos,
          GImNodes->Style.PinCircleRadius,
          pin_color,
          circle_num_segments,
          GImNodes->Style.PinLineThickness);
    } break;
    case ImNodesPinShape_CircleFilled: {
      GImNodes->CanvasDrawList->AddCircleFilled(
          pin_pos, GImNodes->Style.PinCircleRadius, pin_color, circle_num_segments);
    } break;
    case ImNodesPinShape_Quad: {
      const QuadOffsets offset = CalculateQuadOffsets(GImNodes->Style.PinQuadSideLength);
      GImNodes->CanvasDrawList->AddQuad(pin_pos + offset.TopLeft,
          pin_pos + offset.BottomLeft,
          pin_pos + offset.BottomRight,
          pin_pos + offset.TopRight,
          pin_color,
          GImNodes->Style.PinLineThickness);
    } break;
    case ImNodesPinShape_QuadFilled: {
      const QuadOffsets offset = CalculateQuadOffsets(GImNodes->Style.PinQuadSideLength);
      GImNodes->CanvasDrawList->AddQuadFilled(pin_pos + offset.TopLeft,
          pin_pos + offset.BottomLeft,
          pin_pos + offset.BottomRight,
          pin_pos + offset.TopRight,
          pin_color);
    } break;
    case ImNodesPinShape_Triangle: {
      const TriangleOffsets offset =
          CalculateTriangleOffsets(GImNodes->Style.PinTriangleSideLength);
      GImNodes->CanvasDrawList->AddTriangle(pin_pos + offset.TopLeft,
          pin_pos + offset.BottomLeft,
          pin_pos + offset.Right,
          pin_color,
          // NOTE: for some weird reason, the line drawn by AddTriangle is
          // much thinner than the lines drawn by AddCircle or AddQuad.
          // Multiplying the line thickness by two seemed to solve the
          // problem at a few different thickness values.
          2.f * GImNodes->Style.PinLineThickness);
    } break;
    case ImNodesPinShape_TriangleFilled: {
      const TriangleOffsets offset =
          CalculateTriangleOffsets(GImNodes->Style.PinTriangleSideLength);
      GImNodes->CanvasDrawList->AddTriangleFilled(
          pin_pos + offset.TopLeft, pin_pos + offset.BottomLeft, pin_pos + offset.Right, pin_color);
    } break;
    default:
      IM_ASSERT(!"Invalid PinShape value!");
      break;
  }
}

void DrawPin(ImNodesEditorContext& editor, const int pin_idx) {
  ImPinData& pin = editor.Pins.Pool[pin_idx];
  const ImRect& parent_node_rect = editor.Nodes.Pool[pin.ParentNodeIdx].Rect;

  pin.Pos = GetScreenSpacePinCoordinates(parent_node_rect, pin.AttributeRect, pin.Type);

  ImU32 pin_color = pin.ColorStyle.Background;

  if (GImNodes->HoveredPinIdx == pin_idx) {
    pin_color = pin.ColorStyle.Hovered;
  }

  DrawPinShape(pin.Pos, pin, pin_color);
}

void DrawNode(ImNodesEditorContext& editor, const int node_idx) {
  const ImNodeData& node = editor.Nodes.Pool[node_idx];
  ImGui::SetCursorPos(node.Origin + editor.Panning);

  const bool node_hovered =
      GImNodes->HoveredNodeIdx == node_idx &&
      editor.ClickInteraction.Type != ImNodesClickInteractionType_BoxSelection;

  ImU32 node_background = node.ColorStyle.Background;
  ImU32 titlebar_background = node.ColorStyle.Titlebar;

  if (editor.SelectedNodeIndices.contains(node_idx)) {
    node_background = node.ColorStyle.BackgroundSelected;
    titlebar_background = node.ColorStyle.TitlebarSelected;
  } else if (node_hovered) {
    node_background = node.ColorStyle.BackgroundHovered;
    titlebar_background = node.ColorStyle.TitlebarHovered;
  }

  {
    // node base
    GImNodes->CanvasDrawList->AddRectFilled(
        node.Rect.Min, node.Rect.Max, node_background, node.LayoutStyle.CornerRounding);

    // title bar:
    if (node.TitleBarContentRect.GetHeight() > 0.F) {
      const ImRect title_bar_rect = GetNodeTitleRect(node);

      GImNodes->CanvasDrawList->AddRectFilled(title_bar_rect.Min,
          title_bar_rect.Max,
          titlebar_background,
          node.LayoutStyle.CornerRounding,
          ImDrawFlags_RoundCornersTop);
    }

    if ((GImNodes->Style.Flags & ImNodesStyleFlags_NodeOutline) != 0) {
      GImNodes->CanvasDrawList->AddRect(node.Rect.Min,
          node.Rect.Max,
          node.ColorStyle.Outline,
          node.LayoutStyle.CornerRounding,
          ImDrawFlags_RoundCornersAll,
          node.LayoutStyle.BorderThickness);
    }
  }

  for (const int pin_indice : node.PinIndices) {
    DrawPin(editor, pin_indice);
  }

  if (node_hovered) {
    GImNodes->HoveredNodeIdx = node_idx;
  }
}

void DrawLink(ImNodesEditorContext& editor, const int link_idx) {
  const ImLinkData& link = editor.Links.Pool[link_idx];
  const ImPinData& start_pin = editor.Pins.Pool[link.StartPinIdx];
  const ImPinData& end_pin = editor.Pins.Pool[link.EndPinIdx];

  const CubicBezier cubic_bezier = GetCubicBezier(
      start_pin.Pos, end_pin.Pos, start_pin.Type, GImNodes->Style.LinkLineSegmentsPerLength);

  const bool link_hovered =
      GImNodes->HoveredLinkIdx == link_idx &&
      editor.ClickInteraction.Type != ImNodesClickInteractionType_BoxSelection;

  if (link_hovered) {
    GImNodes->HoveredLinkIdx = link_idx;
  }

  // It's possible for a link to be deleted in begin_link_interaction. A user
  // may detach a link, resulting in the link wire snapping to the mouse
  // position.
  //
  // In other words, skip rendering the link if it was deleted.
  if (GImNodes->DeletedLinkIdx == link_idx) {
    return;
  }

  ImU32 link_color = link.ColorStyle.Base;
  if (editor.SelectedLinkIndices.contains(link_idx)) {
    link_color = link.ColorStyle.Selected;
  } else if (link_hovered) {
    link_color = link.ColorStyle.Hovered;
  }

  GImNodes->CanvasDrawList->AddBezierCubic(cubic_bezier.P0,
      cubic_bezier.P1,
      cubic_bezier.P2,
      cubic_bezier.P3,
      link_color,
      GImNodes->Style.LinkThickness,
      cubic_bezier.NumSegments);
}

void BeginPinAttribute(const int id,
    const ImNodesAttributeType type,
    const ImNodesPinShape shape,
    const int node_idx) {
  // Make sure to call BeginNode() before calling
  // BeginAttribute()
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_Node);
  GImNodes->CurrentScope = ImNodesScope_Attribute;

  ImGui::BeginGroup();
  ImGui::PushID(id);

  ImNodesEditorContext& editor = EditorContextGet();

  GImNodes->CurrentAttributeId = id;

  const int pin_idx = ObjectPoolFindOrCreateIndex(editor.Pins, id);
  GImNodes->CurrentPinIdx = pin_idx;
  ImPinData& pin = editor.Pins.Pool[pin_idx];
  pin.Id = id;
  pin.ParentNodeIdx = node_idx;
  pin.Type = type;
  pin.Shape = shape;
  pin.Flags = GImNodes->CurrentAttributeFlags;
  pin.ColorStyle.Background = GImNodes->Style.Colors[ImNodesCol_Pin];
  pin.ColorStyle.Hovered = GImNodes->Style.Colors[ImNodesCol_PinHovered];
}

void EndPinAttribute() {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_Attribute);
  GImNodes->CurrentScope = ImNodesScope_Node;

  ImGui::PopID();
  ImGui::EndGroup();

  if (ImGui::IsItemActive()) {
    GImNodes->ActiveAttribute = true;
    GImNodes->ActiveAttributeId = GImNodes->CurrentAttributeId;
  }

  ImNodesEditorContext& editor = EditorContextGet();
  ImPinData& pin = editor.Pins.Pool[GImNodes->CurrentPinIdx];
  ImNodeData& node = editor.Nodes.Pool[GImNodes->CurrentNodeIdx];
  pin.AttributeRect = GetItemRect();
  node.PinIndices.push_back(GImNodes->CurrentPinIdx);
}

void Initialize(ImNodesContext* context) {
  context->CanvasOriginScreenSpace = ImVec2(0.0F, 0.0F);
  context->CanvasRectScreenSpace = ImRect(ImVec2(0.F, 0.F), ImVec2(0.F, 0.F));
  context->CurrentScope = ImNodesScope_None;

  context->CurrentPinIdx = INT_MAX;
  context->CurrentNodeIdx = INT_MAX;

  context->DefaultEditorCtx = EditorContextCreate();
  context->EditorCtx = context->DefaultEditorCtx;

  context->CurrentAttributeFlags = ImNodesAttributeFlags_None;
  context->AttributeFlagStack.push_back(GImNodes->CurrentAttributeFlags);

  StyleColorsDark(&context->Style);
}

void Shutdown(ImNodesContext* ctx) {
  EditorContextFree(ctx->DefaultEditorCtx);
}

// [SECTION] minimap

static inline bool IsMiniMapActive() {
  const ImNodesEditorContext& editor = EditorContextGet();
  return editor.MiniMapEnabled && editor.MiniMapSizeFraction > 0.0F;
}

static inline bool IsMiniMapHovered() {
  const ImNodesEditorContext& editor = EditorContextGet();
  return IsMiniMapActive() && ImGui::IsMouseHoveringRect(editor.MiniMapRectScreenSpace.Min,
                                  editor.MiniMapRectScreenSpace.Max);
}

static inline void CalcMiniMapLayout() {
  ImNodesEditorContext& editor = EditorContextGet();
  const ImVec2 offset = GImNodes->Style.MiniMapOffset;
  const ImVec2 border = GImNodes->Style.MiniMapPadding;
  const ImRect editor_rect = GImNodes->CanvasRectScreenSpace;

  // Compute the size of the mini-map area
  ImVec2 mini_map_size;
  float mini_map_scaling{};
  {
    const ImVec2 max_size =
        ImFloor(editor_rect.GetSize() * editor.MiniMapSizeFraction - border * 2.0F);
    const float max_size_aspect_ratio = max_size.x / max_size.y;
    const ImVec2 grid_content_size = editor.GridContentBounds.IsInverted()
                                         ? max_size
                                         : ImFloor(editor.GridContentBounds.GetSize());
    const float grid_content_aspect_ratio = grid_content_size.x / grid_content_size.y;
    mini_map_size = ImFloor(grid_content_aspect_ratio > max_size_aspect_ratio
                                ? ImVec2(max_size.x, max_size.x / grid_content_aspect_ratio)
                                : ImVec2(max_size.y * grid_content_aspect_ratio, max_size.y));
    mini_map_scaling = mini_map_size.x / grid_content_size.x;
  }

  // Compute location of the mini-map
  ImVec2 mini_map_pos;
  {
    ImVec2 align;

    switch (editor.MiniMapLocation) {
      case ImNodesMiniMapLocation_BottomRight:
        align.x = 1.0F;
        align.y = 1.0F;
        break;
      case ImNodesMiniMapLocation_BottomLeft:
        align.x = 0.0F;
        align.y = 1.0F;
        break;
      case ImNodesMiniMapLocation_TopRight:
        align.x = 1.0F;
        align.y = 0.0F;
        break;
      case ImNodesMiniMapLocation_TopLeft:  // [[fallthrough]]
      default:
        align.x = 0.0F;
        align.y = 0.0F;
        break;
    }

    const ImVec2 top_left_pos = editor_rect.Min + offset + border;
    const ImVec2 bottom_right_pos = editor_rect.Max - offset - border - mini_map_size;
    mini_map_pos = ImFloor(ImLerp(top_left_pos, bottom_right_pos, align));
  }

  editor.MiniMapRectScreenSpace =
      ImRect(mini_map_pos - border, mini_map_pos + mini_map_size + border);
  editor.MiniMapContentScreenSpace = ImRect(mini_map_pos, mini_map_pos + mini_map_size);
  editor.MiniMapScaling = mini_map_scaling;
}

static void MiniMapDrawNode(ImNodesEditorContext& editor, const int node_idx) {
  const ImNodeData& node = editor.Nodes.Pool[node_idx];

  const ImRect node_rect = ScreenSpaceToMiniMapSpace(editor, node.Rect);

  // Round to near whole pixel value for corner-rounding to prevent visual glitches
  const float mini_map_node_rounding =
      floorf(node.LayoutStyle.CornerRounding * editor.MiniMapScaling);

  ImU32 mini_map_node_background{};

  if (editor.ClickInteraction.Type == ImNodesClickInteractionType_None &&
      ImGui::IsMouseHoveringRect(node_rect.Min, node_rect.Max)) {
    mini_map_node_background = GImNodes->Style.Colors[ImNodesCol_MiniMapNodeBackgroundHovered];

    // Run user callback when hovering a mini-map node
    if (editor.MiniMapNodeHoveringCallback != nullptr) {
      editor.MiniMapNodeHoveringCallback(node.Id, editor.MiniMapNodeHoveringCallbackUserData);
    }
  } else if (editor.SelectedNodeIndices.contains(node_idx)) {
    mini_map_node_background = GImNodes->Style.Colors[ImNodesCol_MiniMapNodeBackgroundSelected];
  } else {
    mini_map_node_background = GImNodes->Style.Colors[ImNodesCol_MiniMapNodeBackground];
  }

  const ImU32 mini_map_node_outline = GImNodes->Style.Colors[ImNodesCol_MiniMapNodeOutline];

  GImNodes->CanvasDrawList->AddRectFilled(
      node_rect.Min, node_rect.Max, mini_map_node_background, mini_map_node_rounding);

  GImNodes->CanvasDrawList->AddRect(
      node_rect.Min, node_rect.Max, mini_map_node_outline, mini_map_node_rounding);
}

static void MiniMapDrawLink(ImNodesEditorContext& editor, const int link_idx) {
  const ImLinkData& link = editor.Links.Pool[link_idx];
  const ImPinData& start_pin = editor.Pins.Pool[link.StartPinIdx];
  const ImPinData& end_pin = editor.Pins.Pool[link.EndPinIdx];

  const CubicBezier cubic_bezier = GetCubicBezier(ScreenSpaceToMiniMapSpace(editor, start_pin.Pos),
      ScreenSpaceToMiniMapSpace(editor, end_pin.Pos),
      start_pin.Type,
      GImNodes->Style.LinkLineSegmentsPerLength / editor.MiniMapScaling);

  // It's possible for a link to be deleted in begin_link_interaction. A user
  // may detach a link, resulting in the link wire snapping to the mouse
  // position.
  //
  // In other words, skip rendering the link if it was deleted.
  if (GImNodes->DeletedLinkIdx == link_idx) {
    return;
  }

  const ImU32 link_color =
      GImNodes->Style
          .Colors[editor.SelectedLinkIndices.contains(link_idx) ? ImNodesCol_MiniMapLinkSelected
                                                                : ImNodesCol_MiniMapLink];

  GImNodes->CanvasDrawList->AddBezierCubic(cubic_bezier.P0,
      cubic_bezier.P1,
      cubic_bezier.P2,
      cubic_bezier.P3,
      link_color,
      GImNodes->Style.LinkThickness * editor.MiniMapScaling,
      cubic_bezier.NumSegments);
}

static void MiniMapUpdate() {
  ImNodesEditorContext& editor = EditorContextGet();

  ImU32 mini_map_background{};

  if (IsMiniMapHovered()) {
    mini_map_background = GImNodes->Style.Colors[ImNodesCol_MiniMapBackgroundHovered];
  } else {
    mini_map_background = GImNodes->Style.Colors[ImNodesCol_MiniMapBackground];
  }

  // Create a child window bellow mini-map, so it blocks all mouse interaction on canvas.
  const int flags = ImGuiWindowFlags_NoBackground;
  ImGui::SetCursorScreenPos(editor.MiniMapRectScreenSpace.Min);
  ImGui::BeginChild("minimap", editor.MiniMapRectScreenSpace.GetSize(), 0, flags);

  const ImRect& mini_map_rect = editor.MiniMapRectScreenSpace;

  // Draw minimap background and border
  GImNodes->CanvasDrawList->AddRectFilled(
      mini_map_rect.Min, mini_map_rect.Max, mini_map_background);

  GImNodes->CanvasDrawList->AddRect(
      mini_map_rect.Min, mini_map_rect.Max, GImNodes->Style.Colors[ImNodesCol_MiniMapOutline]);

  // Clip draw list items to mini-map rect (after drawing background/outline)
  GImNodes->CanvasDrawList->PushClipRect(
      mini_map_rect.Min, mini_map_rect.Max, true /* intersect with editor clip-rect */);

  // Draw links first, so they appear under nodes, and we can use the same draw channel
  for (int link_idx = 0; link_idx < editor.Links.Pool.size(); ++link_idx) {
    if (editor.Links.InUse[link_idx]) {
      MiniMapDrawLink(editor, link_idx);
    }
  }

  for (int node_idx = 0; node_idx < editor.Nodes.Pool.size(); ++node_idx) {
    if (editor.Nodes.InUse[node_idx]) {
      MiniMapDrawNode(editor, node_idx);
    }
  }

  // Draw editor canvas rect inside mini-map
  {
    const ImU32 canvas_color = GImNodes->Style.Colors[ImNodesCol_MiniMapCanvas];
    const ImU32 outline_color = GImNodes->Style.Colors[ImNodesCol_MiniMapCanvasOutline];
    const ImRect rect = ScreenSpaceToMiniMapSpace(editor, GImNodes->CanvasRectScreenSpace);

    GImNodes->CanvasDrawList->AddRectFilled(rect.Min, rect.Max, canvas_color);
    GImNodes->CanvasDrawList->AddRect(rect.Min, rect.Max, outline_color);
  }

  // Have to pop mini-map clip rect
  GImNodes->CanvasDrawList->PopClipRect();

  const bool mini_map_is_hovered = ImGui::IsWindowHovered();

  ImGui::EndChild();

  const bool center_on_click = mini_map_is_hovered && ImGui::IsMouseDown(ImGuiMouseButton_Left) &&
                               editor.ClickInteraction.Type == ImNodesClickInteractionType_None &&
                               !GImNodes->NodeIdxSubmissionOrder.empty();
  if (center_on_click) {
    const ImVec2 target = MiniMapSpaceToGridSpace(editor, ImGui::GetMousePos());
    const ImVec2 center = GImNodes->CanvasRectScreenSpace.GetSize() * 0.5F;
    editor.Panning = ImFloor(center - target);
  }

  // Reset callback info after use
  editor.MiniMapNodeHoveringCallback = nullptr;
  editor.MiniMapNodeHoveringCallbackUserData = nullptr;
}

// [SECTION] selection helpers

template <typename T>
void SelectObject(const ImObjectPool<T>& objects, ImVector<int>& selected_indices, const int id) {
  const int idx = ObjectPoolFind(objects, id);
  IM_ASSERT(idx >= 0);
  IM_ASSERT(selected_indices.find(idx) == selected_indices.end());
  selected_indices.push_back(idx);
}

template <typename T>
void ClearObjectSelection(
    const ImObjectPool<T>& objects, ImVector<int>& selected_indices, const int id) {
  const int idx = ObjectPoolFind(objects, id);
  IM_ASSERT(idx >= 0);
  IM_ASSERT(selected_indices.find(idx) != selected_indices.end());
  selected_indices.find_erase_unsorted(idx);
}

template <typename T>
bool IsObjectSelected(
    const ImObjectPool<T>& objects, ImVector<int>& selected_indices, const int id) {
  const int idx = ObjectPoolFind(objects, id);
  return selected_indices.find(idx) != selected_indices.end();
}

}  // namespace
}  // namespace ImNodes

// [SECTION] API implementation

ImNodesIO::EmulateThreeButtonMouse::EmulateThreeButtonMouse() : Modifier(nullptr) {}

ImNodesIO::LinkDetachWithModifierClick::LinkDetachWithModifierClick() : Modifier(nullptr) {}

ImNodesIO::MultipleSelectModifier::MultipleSelectModifier() : Modifier(nullptr) {}

ImNodesIO::ImNodesIO() : AltMouseButton(ImGuiMouseButton_Middle), AutoPanningSpeed(1000.0F) {}

ImNodesStyle::ImNodesStyle()
    : GridSpacing(24.F),
      NodeCornerRounding(4.F),
      NodePadding(8.F, 8.F),
      NodeBorderThickness(1.F),
      LinkThickness(3.F),
      LinkLineSegmentsPerLength(0.1F),
      LinkHoverDistance(10.F),
      PinCircleRadius(4.F),
      PinQuadSideLength(7.F),
      PinTriangleSideLength(9.5F),
      PinLineThickness(1.F),
      PinHoverRadius(10.F),
      PinOffset(0.F),
      MiniMapPadding(8.0F, 8.0F),
      MiniMapOffset(4.0F, 4.0F),
      Flags(ImNodesStyleFlags_NodeOutline | ImNodesStyleFlags_GridLines),
      Colors() {}

namespace ImNodes {
ImNodesContext* CreateContext() {
  auto* ctx = IM_NEW(ImNodesContext)();
  if (GImNodes == nullptr) {
    SetCurrentContext(ctx);
  }
  Initialize(ctx);
  return ctx;
}

void DestroyContext(ImNodesContext* ctx) {
  if (ctx == nullptr) {
    ctx = GImNodes;
  }
  Shutdown(ctx);
  if (GImNodes == ctx) {
    SetCurrentContext(nullptr);
  }
  IM_DELETE(ctx);
}

ImNodesContext* GetCurrentContext() {
  return GImNodes;
}

void SetCurrentContext(ImNodesContext* ctx) {
  GImNodes = ctx;
}

ImNodesEditorContext* EditorContextCreate() {
  void* mem = ImGui::MemAlloc(sizeof(ImNodesEditorContext));
  new (mem) ImNodesEditorContext();
  return (ImNodesEditorContext*)mem;
}

void EditorContextFree(ImNodesEditorContext* ctx) {
  ctx->~ImNodesEditorContext();
  ImGui::MemFree(ctx);
}

void EditorContextSet(ImNodesEditorContext* ctx) {
  GImNodes->EditorCtx = ctx;
}

ImVec2 EditorContextGetPanning() {
  const ImNodesEditorContext& editor = EditorContextGet();
  return editor.Panning;
}

void EditorContextResetPanning(const ImVec2& pos) {
  ImNodesEditorContext& editor = EditorContextGet();
  editor.Panning = pos;
}

void EditorContextMoveToNode(int node_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  const ImNodeData& node = ObjectPoolFindOrCreateObject(editor.Nodes, node_id);

  editor.Panning.x = -node.Origin.x;
  editor.Panning.y = -node.Origin.y;
}

void SetImGuiContext(ImGuiContext* ctx) {
  ImGui::SetCurrentContext(ctx);
}

ImNodesIO& GetIO() {
  return GImNodes->Io;
}

ImNodesStyle& GetStyle() {
  return GImNodes->Style;
}

void StyleColorsDark(ImNodesStyle* dest) {
  if (dest == nullptr) {
    dest = &GImNodes->Style;
  }

  dest->Colors[ImNodesCol_NodeBackground] = IM_COL32(50, 50, 50, 255);
  dest->Colors[ImNodesCol_NodeBackgroundHovered] = IM_COL32(75, 75, 75, 255);
  dest->Colors[ImNodesCol_NodeBackgroundSelected] = IM_COL32(75, 75, 75, 255);
  dest->Colors[ImNodesCol_NodeOutline] = IM_COL32(100, 100, 100, 255);
  // title bar colors match ImGui's titlebg colors
  dest->Colors[ImNodesCol_TitleBar] = IM_COL32(41, 74, 122, 255);
  dest->Colors[ImNodesCol_TitleBarHovered] = IM_COL32(66, 150, 250, 255);
  dest->Colors[ImNodesCol_TitleBarSelected] = IM_COL32(66, 150, 250, 255);
  // link colors match ImGui's slider grab colors
  dest->Colors[ImNodesCol_Link] = IM_COL32(61, 133, 224, 200);
  dest->Colors[ImNodesCol_LinkHovered] = IM_COL32(66, 150, 250, 255);
  dest->Colors[ImNodesCol_LinkSelected] = IM_COL32(66, 150, 250, 255);
  // pin colors match ImGui's button colors
  dest->Colors[ImNodesCol_Pin] = IM_COL32(53, 150, 250, 180);
  dest->Colors[ImNodesCol_PinHovered] = IM_COL32(53, 150, 250, 255);

  dest->Colors[ImNodesCol_BoxSelector] = IM_COL32(61, 133, 224, 30);
  dest->Colors[ImNodesCol_BoxSelectorOutline] = IM_COL32(61, 133, 224, 150);

  dest->Colors[ImNodesCol_GridBackground] = IM_COL32(40, 40, 50, 200);
  dest->Colors[ImNodesCol_GridLine] = IM_COL32(200, 200, 200, 40);
  dest->Colors[ImNodesCol_GridLinePrimary] = IM_COL32(240, 240, 240, 60);

  // minimap colors
  dest->Colors[ImNodesCol_MiniMapBackground] = IM_COL32(25, 25, 25, 150);
  dest->Colors[ImNodesCol_MiniMapBackgroundHovered] = IM_COL32(25, 25, 25, 200);
  dest->Colors[ImNodesCol_MiniMapOutline] = IM_COL32(150, 150, 150, 100);
  dest->Colors[ImNodesCol_MiniMapOutlineHovered] = IM_COL32(150, 150, 150, 200);
  dest->Colors[ImNodesCol_MiniMapNodeBackground] = IM_COL32(200, 200, 200, 100);
  dest->Colors[ImNodesCol_MiniMapNodeBackgroundHovered] = IM_COL32(200, 200, 200, 255);
  dest->Colors[ImNodesCol_MiniMapNodeBackgroundSelected] =
      dest->Colors[ImNodesCol_MiniMapNodeBackgroundHovered];
  dest->Colors[ImNodesCol_MiniMapNodeOutline] = IM_COL32(200, 200, 200, 100);
  dest->Colors[ImNodesCol_MiniMapLink] = dest->Colors[ImNodesCol_Link];
  dest->Colors[ImNodesCol_MiniMapLinkSelected] = dest->Colors[ImNodesCol_LinkSelected];
  dest->Colors[ImNodesCol_MiniMapCanvas] = IM_COL32(200, 200, 200, 25);
  dest->Colors[ImNodesCol_MiniMapCanvasOutline] = IM_COL32(200, 200, 200, 200);
}

void StyleColorsClassic(ImNodesStyle* dest) {
  if (dest == nullptr) {
    dest = &GImNodes->Style;
  }

  dest->Colors[ImNodesCol_NodeBackground] = IM_COL32(50, 50, 50, 255);
  dest->Colors[ImNodesCol_NodeBackgroundHovered] = IM_COL32(75, 75, 75, 255);
  dest->Colors[ImNodesCol_NodeBackgroundSelected] = IM_COL32(75, 75, 75, 255);
  dest->Colors[ImNodesCol_NodeOutline] = IM_COL32(100, 100, 100, 255);
  dest->Colors[ImNodesCol_TitleBar] = IM_COL32(69, 69, 138, 255);
  dest->Colors[ImNodesCol_TitleBarHovered] = IM_COL32(82, 82, 161, 255);
  dest->Colors[ImNodesCol_TitleBarSelected] = IM_COL32(82, 82, 161, 255);
  dest->Colors[ImNodesCol_Link] = IM_COL32(255, 255, 255, 100);
  dest->Colors[ImNodesCol_LinkHovered] = IM_COL32(105, 99, 204, 153);
  dest->Colors[ImNodesCol_LinkSelected] = IM_COL32(105, 99, 204, 153);
  dest->Colors[ImNodesCol_Pin] = IM_COL32(89, 102, 156, 170);
  dest->Colors[ImNodesCol_PinHovered] = IM_COL32(102, 122, 179, 200);
  dest->Colors[ImNodesCol_BoxSelector] = IM_COL32(82, 82, 161, 100);
  dest->Colors[ImNodesCol_BoxSelectorOutline] = IM_COL32(82, 82, 161, 255);
  dest->Colors[ImNodesCol_GridBackground] = IM_COL32(40, 40, 50, 200);
  dest->Colors[ImNodesCol_GridLine] = IM_COL32(200, 200, 200, 40);
  dest->Colors[ImNodesCol_GridLinePrimary] = IM_COL32(240, 240, 240, 60);

  // minimap colors
  dest->Colors[ImNodesCol_MiniMapBackground] = IM_COL32(25, 25, 25, 100);
  dest->Colors[ImNodesCol_MiniMapBackgroundHovered] = IM_COL32(25, 25, 25, 200);
  dest->Colors[ImNodesCol_MiniMapOutline] = IM_COL32(150, 150, 150, 100);
  dest->Colors[ImNodesCol_MiniMapOutlineHovered] = IM_COL32(150, 150, 150, 200);
  dest->Colors[ImNodesCol_MiniMapNodeBackground] = IM_COL32(200, 200, 200, 100);
  dest->Colors[ImNodesCol_MiniMapNodeBackgroundSelected] =
      dest->Colors[ImNodesCol_MiniMapNodeBackgroundHovered];
  dest->Colors[ImNodesCol_MiniMapNodeBackgroundSelected] = IM_COL32(200, 200, 240, 255);
  dest->Colors[ImNodesCol_MiniMapNodeOutline] = IM_COL32(200, 200, 200, 100);
  dest->Colors[ImNodesCol_MiniMapLink] = dest->Colors[ImNodesCol_Link];
  dest->Colors[ImNodesCol_MiniMapLinkSelected] = dest->Colors[ImNodesCol_LinkSelected];
  dest->Colors[ImNodesCol_MiniMapCanvas] = IM_COL32(200, 200, 200, 25);
  dest->Colors[ImNodesCol_MiniMapCanvasOutline] = IM_COL32(200, 200, 200, 200);
}

void StyleColorsLight(ImNodesStyle* dest) {
  if (dest == nullptr) {
    dest = &GImNodes->Style;
  }

  dest->Colors[ImNodesCol_NodeBackground] = IM_COL32(240, 240, 240, 255);
  dest->Colors[ImNodesCol_NodeBackgroundHovered] = IM_COL32(240, 240, 240, 255);
  dest->Colors[ImNodesCol_NodeBackgroundSelected] = IM_COL32(240, 240, 240, 255);
  dest->Colors[ImNodesCol_NodeOutline] = IM_COL32(100, 100, 100, 255);
  dest->Colors[ImNodesCol_TitleBar] = IM_COL32(248, 248, 248, 255);
  dest->Colors[ImNodesCol_TitleBarHovered] = IM_COL32(209, 209, 209, 255);
  dest->Colors[ImNodesCol_TitleBarSelected] = IM_COL32(209, 209, 209, 255);
  // original imgui values: 66, 150, 250
  dest->Colors[ImNodesCol_Link] = IM_COL32(66, 150, 250, 100);
  // original imgui values: 117, 138, 204
  dest->Colors[ImNodesCol_LinkHovered] = IM_COL32(66, 150, 250, 242);
  dest->Colors[ImNodesCol_LinkSelected] = IM_COL32(66, 150, 250, 242);
  // original imgui values: 66, 150, 250
  dest->Colors[ImNodesCol_Pin] = IM_COL32(66, 150, 250, 160);
  dest->Colors[ImNodesCol_PinHovered] = IM_COL32(66, 150, 250, 255);
  dest->Colors[ImNodesCol_BoxSelector] = IM_COL32(90, 170, 250, 30);
  dest->Colors[ImNodesCol_BoxSelectorOutline] = IM_COL32(90, 170, 250, 150);
  dest->Colors[ImNodesCol_GridBackground] = IM_COL32(225, 225, 225, 255);
  dest->Colors[ImNodesCol_GridLine] = IM_COL32(180, 180, 180, 100);
  dest->Colors[ImNodesCol_GridLinePrimary] = IM_COL32(120, 120, 120, 100);

  // minimap colors
  dest->Colors[ImNodesCol_MiniMapBackground] = IM_COL32(25, 25, 25, 100);
  dest->Colors[ImNodesCol_MiniMapBackgroundHovered] = IM_COL32(25, 25, 25, 200);
  dest->Colors[ImNodesCol_MiniMapOutline] = IM_COL32(150, 150, 150, 100);
  dest->Colors[ImNodesCol_MiniMapOutlineHovered] = IM_COL32(150, 150, 150, 200);
  dest->Colors[ImNodesCol_MiniMapNodeBackground] = IM_COL32(200, 200, 200, 100);
  dest->Colors[ImNodesCol_MiniMapNodeBackgroundSelected] =
      dest->Colors[ImNodesCol_MiniMapNodeBackgroundHovered];
  dest->Colors[ImNodesCol_MiniMapNodeBackgroundSelected] = IM_COL32(200, 200, 240, 255);
  dest->Colors[ImNodesCol_MiniMapNodeOutline] = IM_COL32(200, 200, 200, 100);
  dest->Colors[ImNodesCol_MiniMapLink] = dest->Colors[ImNodesCol_Link];
  dest->Colors[ImNodesCol_MiniMapLinkSelected] = dest->Colors[ImNodesCol_LinkSelected];
  dest->Colors[ImNodesCol_MiniMapCanvas] = IM_COL32(200, 200, 200, 25);
  dest->Colors[ImNodesCol_MiniMapCanvasOutline] = IM_COL32(200, 200, 200, 200);
}

void BeginNodeEditor() {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_None);
  GImNodes->CurrentScope = ImNodesScope_Editor;

  // Reset state from previous pass

  ImNodesEditorContext& editor = EditorContextGet();
  editor.AutoPanningDelta = ImVec2(0, 0);
  editor.GridContentBounds = ImRect(FLT_MAX, FLT_MAX, -FLT_MAX, -FLT_MAX);
  editor.MiniMapEnabled = false;
  ObjectPoolReset(editor.Nodes);
  ObjectPoolReset(editor.Pins);
  ObjectPoolReset(editor.Links);

  GImNodes->HoveredNodeIdx.Reset();
  GImNodes->HoveredLinkIdx.Reset();
  GImNodes->HoveredPinIdx.Reset();
  GImNodes->DeletedLinkIdx.Reset();
  GImNodes->SnapLinkIdx.Reset();

  GImNodes->NodeIndicesOverlappingWithMouse.clear();

  GImNodes->ImNodesUIState = ImNodesUIState_None;

  GImNodes->MousePos = ImGui::GetIO().MousePos;
  GImNodes->LeftMouseClicked = ImGui::IsMouseClicked(0);
  GImNodes->LeftMouseReleased = ImGui::IsMouseReleased(0);
  GImNodes->LeftMouseDragging = ImGui::IsMouseDragging(0, 0.0F);
  GImNodes->AltMouseClicked =
      (GImNodes->Io.EmulateThreeButtonMouse.Modifier != nullptr &&
          *GImNodes->Io.EmulateThreeButtonMouse.Modifier && GImNodes->LeftMouseClicked) ||
      ImGui::IsMouseClicked(GImNodes->Io.AltMouseButton);
  GImNodes->AltMouseDragging =
      (GImNodes->Io.EmulateThreeButtonMouse.Modifier != nullptr && GImNodes->LeftMouseDragging &&
          (*GImNodes->Io.EmulateThreeButtonMouse.Modifier)) ||
      ImGui::IsMouseDragging(GImNodes->Io.AltMouseButton, 0.0F);
  GImNodes->AltMouseScrollDelta = ImGui::GetIO().MouseWheel;
  GImNodes->MultipleSelectModifier = (GImNodes->Io.MultipleSelectModifier.Modifier != nullptr
                                          ? *GImNodes->Io.MultipleSelectModifier.Modifier
                                          : ImGui::GetIO().KeyCtrl);

  GImNodes->ActiveAttribute = false;

  ImGui::BeginGroup();
  {
    ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(1.F, 1.F));
    ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(0.F, 0.F));
    ImGui::PushStyleColor(ImGuiCol_ChildBg, GImNodes->Style.Colors[ImNodesCol_GridBackground]);
    ImGui::BeginChild("scrolling_region",
        ImVec2(0.F, 0.F),
        true,
        ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoMove |
            ImGuiWindowFlags_NoScrollWithMouse);
    GImNodes->CanvasOriginScreenSpace = ImGui::GetCursorScreenPos();

    // NOTE: we have to fetch the canvas draw list *after* we call
    // BeginChild(), otherwise the ImGui UI elements are going to be
    // rendered into the parent window draw list.
    DrawListSet(ImGui::GetWindowDrawList());

    {
      const ImVec2 canvas_size = ImGui::GetWindowSize();
      GImNodes->CanvasRectScreenSpace =
          ImRect(EditorSpaceToScreenSpace(ImVec2(0.F, 0.F)), EditorSpaceToScreenSpace(canvas_size));

      if (GImNodes->Style.Flags & ImNodesStyleFlags_GridLines) {
        DrawGrid(editor, canvas_size);
      }
    }
  }
}

void EndNodeEditor() {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_Editor);
  GImNodes->CurrentScope = ImNodesScope_None;

  ImNodesEditorContext& editor = EditorContextGet();

  const bool no_grid_content = editor.GridContentBounds.IsInverted();
  if (no_grid_content) {
    editor.GridContentBounds = ScreenSpaceToGridSpace(editor, GImNodes->CanvasRectScreenSpace);
  }

  // Detect ImGui interaction first, because it blocks interaction with the rest of the UI

  if (GImNodes->LeftMouseClicked && ImGui::IsAnyItemActive()) {
    editor.ClickInteraction.Type = ImNodesClickInteractionType_ImGuiItem;
  }

  // Detect which UI element is being hovered over. Detection is done in a hierarchical fashion,
  // because a UI element being hovered excludes any other as being hovered over.

  // Don't do hovering detection for nodes/links/pins when interacting with the mini-map, since
  // it's an *overlay* with its own interaction behavior and must have precedence during mouse
  // interaction.

  if ((editor.ClickInteraction.Type == ImNodesClickInteractionType_None ||
          editor.ClickInteraction.Type == ImNodesClickInteractionType_LinkCreation) &&
      MouseInCanvas() && !IsMiniMapHovered()) {
    // Pins needs some special care. We need to check the depth stack to see which pins are
    // being occluded by other nodes.
    ResolveOccludedPins(editor, GImNodes->OccludedPinIndices);

    GImNodes->HoveredPinIdx = ResolveHoveredPin(editor.Pins, GImNodes->OccludedPinIndices);

    if (!GImNodes->HoveredPinIdx.HasValue()) {
      // Resolve which node is actually on top and being hovered using the depth stack.
      GImNodes->HoveredNodeIdx = ResolveHoveredNode(editor.NodeDepthOrder);
    }

    // We don't check for hovered pins here, because if we want to detach a link by clicking and
    // dragging, we need to have both a link and pin hovered.
    if (!GImNodes->HoveredNodeIdx.HasValue()) {
      GImNodes->HoveredLinkIdx = ResolveHoveredLink(editor.Links, editor.Pins);
    }
  }

  for (int node_idx = 0; node_idx < editor.Nodes.Pool.size(); ++node_idx) {
    if (editor.Nodes.InUse[node_idx]) {
      DrawListActivateNodeBackground(node_idx);
      DrawNode(editor, node_idx);
    }
  }

  // In order to render the links underneath the nodes, we want to first select the bottom draw
  // channel.
  GImNodes->CanvasDrawList->ChannelsSetCurrent(0);

  for (int link_idx = 0; link_idx < editor.Links.Pool.size(); ++link_idx) {
    if (editor.Links.InUse[link_idx]) {
      DrawLink(editor, link_idx);
    }
  }

  // Render the click interaction UI elements (partial links, box selector) on top of everything
  // else.

  DrawListAppendClickInteractionChannel();
  DrawListActivateClickInteractionChannel();

  if (IsMiniMapActive()) {
    CalcMiniMapLayout();
    MiniMapUpdate();
  }

  // Handle node graph interaction

  if (!IsMiniMapHovered()) {
    if (GImNodes->LeftMouseClicked && GImNodes->HoveredLinkIdx.HasValue()) {
      BeginLinkInteraction(editor, GImNodes->HoveredLinkIdx.Value(), GImNodes->HoveredPinIdx);
    }

    else if (GImNodes->LeftMouseClicked && GImNodes->HoveredPinIdx.HasValue()) {
      BeginLinkCreation(editor, GImNodes->HoveredPinIdx.Value());
    }

    else if (GImNodes->LeftMouseClicked && GImNodes->HoveredNodeIdx.HasValue()) {
      BeginNodeSelection(editor, GImNodes->HoveredNodeIdx.Value());
    }

    else if (GImNodes->LeftMouseClicked || GImNodes->LeftMouseReleased ||
             GImNodes->AltMouseClicked || GImNodes->AltMouseScrollDelta != 0.F) {
      BeginCanvasInteraction(editor);
    }

    const bool should_auto_pan =
        editor.ClickInteraction.Type == ImNodesClickInteractionType_BoxSelection ||
        editor.ClickInteraction.Type == ImNodesClickInteractionType_LinkCreation ||
        editor.ClickInteraction.Type == ImNodesClickInteractionType_Node;
    if (should_auto_pan && !MouseInCanvas()) {
      const ImVec2 mouse = ImGui::GetMousePos();
      const ImVec2 center = GImNodes->CanvasRectScreenSpace.GetCenter();
      ImVec2 direction = (center - mouse);
      direction = direction * ImInvLength(direction, 0.0);

      editor.AutoPanningDelta =
          direction * ImGui::GetIO().DeltaTime * GImNodes->Io.AutoPanningSpeed;
      editor.Panning += editor.AutoPanningDelta;
    }
  }
  ClickInteractionUpdate(editor);

  // At this point, draw commands have been issued for all nodes (and pins). Update the node pool
  // to detect unused node slots and remove those indices from the depth stack before sorting the
  // node draw commands by depth.
  ObjectPoolUpdate(editor.Nodes);
  ObjectPoolUpdate(editor.Pins);

  DrawListSortChannelsByDepth(editor.NodeDepthOrder);

  // After the links have been rendered, the link pool can be updated as well.
  ObjectPoolUpdate(editor.Links);

  // Finally, merge the draw channels
  GImNodes->CanvasDrawList->ChannelsMerge();

  // pop style
  ImGui::EndChild();       // end scrolling region
  ImGui::PopStyleColor();  // pop child window background color
  ImGui::PopStyleVar();    // pop window padding
  ImGui::PopStyleVar();    // pop frame padding
  ImGui::EndGroup();
}

void MiniMap(float minimap_size_fraction,
    ImNodesMiniMapLocation location,
    ImNodesMiniMapNodeHoveringCallback node_hovering_callback,
    ImNodesMiniMapNodeHoveringCallbackUserData node_hovering_callback_data) {
  // Check that editor size fraction is sane; must be in the range (0, 1]
  IM_ASSERT(minimap_size_fraction > 0.F && minimap_size_fraction <= 1.F);

  // Remember to call before EndNodeEditor
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_Editor);

  ImNodesEditorContext& editor = EditorContextGet();

  editor.MiniMapEnabled = true;
  editor.MiniMapSizeFraction = minimap_size_fraction;
  editor.MiniMapLocation = location;

  // Set node hovering callback information
  editor.MiniMapNodeHoveringCallback = node_hovering_callback;
  editor.MiniMapNodeHoveringCallbackUserData = node_hovering_callback_data;

  // Actual drawing/updating of the MiniMap is done in EndNodeEditor so that
  // mini map is draw over everything and all pin/link positions are updated
  // correctly relative to their respective nodes. Hence, we must store some of
  // the state for the mini map in GImNodes for the actual drawing/updating
}

void BeginNode(const int node_id) {
  // Remember to call BeginNodeEditor before calling BeginNode
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_Editor);
  GImNodes->CurrentScope = ImNodesScope_Node;

  ImNodesEditorContext& editor = EditorContextGet();

  const int node_idx = ObjectPoolFindOrCreateIndex(editor.Nodes, node_id);
  GImNodes->CurrentNodeIdx = node_idx;

  ImNodeData& node = editor.Nodes.Pool[node_idx];
  node.ColorStyle.Background = GImNodes->Style.Colors[ImNodesCol_NodeBackground];
  node.ColorStyle.BackgroundHovered = GImNodes->Style.Colors[ImNodesCol_NodeBackgroundHovered];
  node.ColorStyle.BackgroundSelected = GImNodes->Style.Colors[ImNodesCol_NodeBackgroundSelected];
  node.ColorStyle.Outline = GImNodes->Style.Colors[ImNodesCol_NodeOutline];
  node.ColorStyle.Titlebar = GImNodes->Style.Colors[ImNodesCol_TitleBar];
  node.ColorStyle.TitlebarHovered = GImNodes->Style.Colors[ImNodesCol_TitleBarHovered];
  node.ColorStyle.TitlebarSelected = GImNodes->Style.Colors[ImNodesCol_TitleBarSelected];
  node.LayoutStyle.CornerRounding = GImNodes->Style.NodeCornerRounding;
  node.LayoutStyle.Padding = GImNodes->Style.NodePadding;
  node.LayoutStyle.BorderThickness = GImNodes->Style.NodeBorderThickness;

  // ImGui::SetCursorPos sets the cursor position, local to the current widget
  // (in this case, the child object started in BeginNodeEditor). Use
  // ImGui::SetCursorScreenPos to set the screen space coordinates directly.
  ImGui::SetCursorPos(GridSpaceToEditorSpace(editor, GetNodeTitleBarOrigin(node)));

  DrawListAddNode(node_idx);
  DrawListActivateCurrentNodeForeground();

  ImGui::PushID(node.Id);
  ImGui::BeginGroup();
}

void EndNode() {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_Node);
  GImNodes->CurrentScope = ImNodesScope_Editor;

  ImNodesEditorContext& editor = EditorContextGet();

  // The node's rectangle depends on the ImGui UI group size.
  ImGui::EndGroup();
  ImGui::PopID();

  ImNodeData& node = editor.Nodes.Pool[GImNodes->CurrentNodeIdx];
  node.Rect = GetItemRect();
  node.Rect.Expand(node.LayoutStyle.Padding);

  editor.GridContentBounds.Add(node.Origin);
  editor.GridContentBounds.Add(node.Origin + node.Rect.GetSize());

  if (node.Rect.Contains(GImNodes->MousePos)) {
    GImNodes->NodeIndicesOverlappingWithMouse.push_back(GImNodes->CurrentNodeIdx);
  }
}

ImVec2 GetNodeDimensions(int node_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  const int node_idx = ObjectPoolFind(editor.Nodes, node_id);
  IM_ASSERT(node_idx != -1);  // invalid node_id
  const ImNodeData& node = editor.Nodes.Pool[node_idx];
  return node.Rect.GetSize();
}

void BeginNodeTitleBar() {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_Node);
  ImGui::BeginGroup();
}

void EndNodeTitleBar() {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_Node);
  ImGui::EndGroup();

  ImNodesEditorContext& editor = EditorContextGet();
  ImNodeData& node = editor.Nodes.Pool[GImNodes->CurrentNodeIdx];
  node.TitleBarContentRect = GetItemRect();

  ImGui::ItemAdd(GetNodeTitleRect(node), ImGui::GetID("title_bar"));

  ImGui::SetCursorPos(GridSpaceToEditorSpace(editor, GetNodeContentOrigin(node)));
}

void BeginInputAttribute(const int id, const ImNodesPinShape shape) {
  BeginPinAttribute(id, ImNodesAttributeType_Input, shape, GImNodes->CurrentNodeIdx);
}

void EndInputAttribute() {
  EndPinAttribute();
}

void BeginOutputAttribute(const int id, const ImNodesPinShape shape) {
  BeginPinAttribute(id, ImNodesAttributeType_Output, shape, GImNodes->CurrentNodeIdx);
}

void EndOutputAttribute() {
  EndPinAttribute();
}

void BeginStaticAttribute(const int id) {
  // Make sure to call BeginNode() before calling BeginAttribute()
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_Node);
  GImNodes->CurrentScope = ImNodesScope_Attribute;

  GImNodes->CurrentAttributeId = id;

  ImGui::BeginGroup();
  ImGui::PushID(id);
}

void EndStaticAttribute() {
  // Make sure to call BeginNode() before calling BeginAttribute()
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_Attribute);
  GImNodes->CurrentScope = ImNodesScope_Node;

  ImGui::PopID();
  ImGui::EndGroup();

  if (ImGui::IsItemActive()) {
    GImNodes->ActiveAttribute = true;
    GImNodes->ActiveAttributeId = GImNodes->CurrentAttributeId;
  }
}

void PushAttributeFlag(const ImNodesAttributeFlags flag) {
  GImNodes->CurrentAttributeFlags |= flag;
  GImNodes->AttributeFlagStack.push_back(GImNodes->CurrentAttributeFlags);
}

void PopAttributeFlag() {
  // PopAttributeFlag called without a matching PushAttributeFlag!
  // The bottom value is always the default value, pushed in Initialize().
  IM_ASSERT(GImNodes->AttributeFlagStack.size() > 1);

  GImNodes->AttributeFlagStack.pop_back();
  GImNodes->CurrentAttributeFlags = GImNodes->AttributeFlagStack.back();
}

void Link(const int id, const int start_attr_id, const int end_attr_id) {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_Editor);

  ImNodesEditorContext& editor = EditorContextGet();
  ImLinkData& link = ObjectPoolFindOrCreateObject(editor.Links, id);
  link.Id = id;
  link.StartPinIdx = ObjectPoolFindOrCreateIndex(editor.Pins, start_attr_id);
  link.EndPinIdx = ObjectPoolFindOrCreateIndex(editor.Pins, end_attr_id);
  link.ColorStyle.Base = GImNodes->Style.Colors[ImNodesCol_Link];
  link.ColorStyle.Hovered = GImNodes->Style.Colors[ImNodesCol_LinkHovered];
  link.ColorStyle.Selected = GImNodes->Style.Colors[ImNodesCol_LinkSelected];

  // Check if this link was created by the current link event
  if ((editor.ClickInteraction.Type == ImNodesClickInteractionType_LinkCreation &&
          ((editor.Pins.Pool[link.EndPinIdx].Flags &
               ImNodesAttributeFlags_EnableLinkCreationOnSnap) != 0) &&
          editor.ClickInteraction.LinkCreation.StartPinIdx == link.StartPinIdx &&
          editor.ClickInteraction.LinkCreation.EndPinIdx == link.EndPinIdx) ||
      (editor.ClickInteraction.LinkCreation.StartPinIdx == link.EndPinIdx &&
          editor.ClickInteraction.LinkCreation.EndPinIdx == link.StartPinIdx)) {
    GImNodes->SnapLinkIdx = ObjectPoolFindOrCreateIndex(editor.Links, id);
  }
}

void PushColorStyle(const ImNodesCol item, unsigned int color) {
  GImNodes->ColorModifierStack.push_back(ImNodesColElement(GImNodes->Style.Colors[item], item));
  GImNodes->Style.Colors[item] = color;
}

void PopColorStyle() {
  IM_ASSERT(!GImNodes->ColorModifierStack.empty());
  const ImNodesColElement elem = GImNodes->ColorModifierStack.back();
  GImNodes->Style.Colors[elem.Item] = elem.Color;
  GImNodes->ColorModifierStack.pop_back();
}

struct ImNodesStyleVarInfo {
  ImGuiDataType Type;
  ImU32 Count;
  ImU32 Offset;
  void* GetVarPtr(ImNodesStyle* style) const {
    return (void*)((unsigned char*)style + Offset);
  }
};

static const ImNodesStyleVarInfo GStyleVarInfo[] = {
    // ImNodesStyleVar_GridSpacing
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, GridSpacing)},
    // ImNodesStyleVar_NodeCornerRounding
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, NodeCornerRounding)},
    // ImNodesStyleVar_NodePadding
    {ImGuiDataType_Float, 2, (ImU32)IM_OFFSETOF(ImNodesStyle, NodePadding)},
    // ImNodesStyleVar_NodeBorderThickness
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, NodeBorderThickness)},
    // ImNodesStyleVar_LinkThickness
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, LinkThickness)},
    // ImNodesStyleVar_LinkLineSegmentsPerLength
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, LinkLineSegmentsPerLength)},
    // ImNodesStyleVar_LinkHoverDistance
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, LinkHoverDistance)},
    // ImNodesStyleVar_PinCircleRadius
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, PinCircleRadius)},
    // ImNodesStyleVar_PinQuadSideLength
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, PinQuadSideLength)},
    // ImNodesStyleVar_PinTriangleSideLength
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, PinTriangleSideLength)},
    // ImNodesStyleVar_PinLineThickness
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, PinLineThickness)},
    // ImNodesStyleVar_PinHoverRadius
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, PinHoverRadius)},
    // ImNodesStyleVar_PinOffset
    {ImGuiDataType_Float, 1, (ImU32)IM_OFFSETOF(ImNodesStyle, PinOffset)},
    // ImNodesStyleVar_MiniMapPadding
    {ImGuiDataType_Float, 2, (ImU32)IM_OFFSETOF(ImNodesStyle, MiniMapPadding)},
    // ImNodesStyleVar_MiniMapOffset
    {ImGuiDataType_Float, 2, (ImU32)IM_OFFSETOF(ImNodesStyle, MiniMapOffset)},
};

static const ImNodesStyleVarInfo* GetStyleVarInfo(ImNodesStyleVar idx) {
  IM_ASSERT(idx >= 0 && idx < ImNodesStyleVar_COUNT);
  IM_ASSERT(IM_ARRAYSIZE(GStyleVarInfo) == ImNodesStyleVar_COUNT);
  return &GStyleVarInfo[idx];
}

void PushStyleVar(const ImNodesStyleVar item, const float value) {
  const ImNodesStyleVarInfo* var_info = GetStyleVarInfo(item);
  if (var_info->Type == ImGuiDataType_Float && var_info->Count == 1) {
    float& style_var = *(float*)var_info->GetVarPtr(&GImNodes->Style);
    GImNodes->StyleModifierStack.push_back(ImNodesStyleVarElement(item, style_var));
    style_var = value;
    return;
  }
  IM_ASSERT(0 && "Called PushStyleVar() float variant but variable is not a float!");
}

void PushStyleVar(const ImNodesStyleVar item, const ImVec2& value) {
  const ImNodesStyleVarInfo* var_info = GetStyleVarInfo(item);
  if (var_info->Type == ImGuiDataType_Float && var_info->Count == 2) {
    ImVec2& style_var = *(ImVec2*)var_info->GetVarPtr(&GImNodes->Style);
    GImNodes->StyleModifierStack.push_back(ImNodesStyleVarElement(item, style_var));
    style_var = value;
    return;
  }
  IM_ASSERT(0 && "Called PushStyleVar() ImVec2 variant but variable is not a ImVec2!");
}

void PopStyleVar(int count) {
  while (count > 0) {
    IM_ASSERT(!GImNodes->StyleModifierStack.empty());
    const ImNodesStyleVarElement style_backup = GImNodes->StyleModifierStack.back();
    GImNodes->StyleModifierStack.pop_back();
    const ImNodesStyleVarInfo* var_info = GetStyleVarInfo(style_backup.Item);
    void* style_var = var_info->GetVarPtr(&GImNodes->Style);
    if (var_info->Type == ImGuiDataType_Float && var_info->Count == 1) {
      ((float*)style_var)[0] = style_backup.FloatValue[0];
    } else if (var_info->Type == ImGuiDataType_Float && var_info->Count == 2) {
      ((float*)style_var)[0] = style_backup.FloatValue[0];
      ((float*)style_var)[1] = style_backup.FloatValue[1];
    }
    count--;
  }
}

void SetNodeScreenSpacePos(const int node_id, const ImVec2& screen_space_pos) {
  ImNodesEditorContext& editor = EditorContextGet();
  ImNodeData& node = ObjectPoolFindOrCreateObject(editor.Nodes, node_id);
  node.Origin = ScreenSpaceToGridSpace(editor, screen_space_pos);
}

void SetNodeEditorSpacePos(const int node_id, const ImVec2& editor_space_pos) {
  ImNodesEditorContext& editor = EditorContextGet();
  ImNodeData& node = ObjectPoolFindOrCreateObject(editor.Nodes, node_id);
  node.Origin = EditorSpaceToGridSpace(editor, editor_space_pos);
}

void SetNodeGridSpacePos(const int node_id, const ImVec2& grid_pos) {
  ImNodesEditorContext& editor = EditorContextGet();
  ImNodeData& node = ObjectPoolFindOrCreateObject(editor.Nodes, node_id);
  node.Origin = grid_pos;
}

void SetNodeDraggable(const int node_id, bool draggable) {
  ImNodesEditorContext& editor = EditorContextGet();
  ImNodeData& node = ObjectPoolFindOrCreateObject(editor.Nodes, node_id);
  node.Draggable = draggable;
}

ImVec2 GetNodeScreenSpacePos(int node_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  const int node_idx = ObjectPoolFind(editor.Nodes, node_id);
  IM_ASSERT(node_idx != -1);
  const ImNodeData& node = editor.Nodes.Pool[node_idx];
  return GridSpaceToScreenSpace(editor, node.Origin);
}

ImVec2 GetNodeEditorSpacePos(int node_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  const int node_idx = ObjectPoolFind(editor.Nodes, node_id);
  IM_ASSERT(node_idx != -1);
  const ImNodeData& node = editor.Nodes.Pool[node_idx];
  return GridSpaceToEditorSpace(editor, node.Origin);
}

ImVec2 GetNodeGridSpacePos(int node_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  const int node_idx = ObjectPoolFind(editor.Nodes, node_id);
  IM_ASSERT(node_idx != -1);
  const ImNodeData& node = editor.Nodes.Pool[node_idx];
  return node.Origin;
}

void SnapNodeToGrid(int node_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  ImNodeData& node = ObjectPoolFindOrCreateObject(editor.Nodes, node_id);
  node.Origin = SnapOriginToGrid(node.Origin);
}

bool IsEditorHovered() {
  return MouseInCanvas();
}

bool IsNodeHovered(int* const node_id) {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_None);
  IM_ASSERT(node_id != nullptr);

  const bool is_hovered = GImNodes->HoveredNodeIdx.HasValue();
  if (is_hovered) {
    const ImNodesEditorContext& editor = EditorContextGet();
    *node_id = editor.Nodes.Pool[GImNodes->HoveredNodeIdx.Value()].Id;
  }
  return is_hovered;
}

bool IsLinkHovered(int* const link_id) {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_None);
  IM_ASSERT(link_id != nullptr);

  const bool is_hovered = GImNodes->HoveredLinkIdx.HasValue();
  if (is_hovered) {
    const ImNodesEditorContext& editor = EditorContextGet();
    *link_id = editor.Links.Pool[GImNodes->HoveredLinkIdx.Value()].Id;
  }
  return is_hovered;
}

bool IsPinHovered(int* const attr) {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_None);
  IM_ASSERT(attr != nullptr);

  const bool is_hovered = GImNodes->HoveredPinIdx.HasValue();
  if (is_hovered) {
    const ImNodesEditorContext& editor = EditorContextGet();
    *attr = editor.Pins.Pool[GImNodes->HoveredPinIdx.Value()].Id;
  }
  return is_hovered;
}

int NumSelectedNodes() {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_None);
  const ImNodesEditorContext& editor = EditorContextGet();
  return editor.SelectedNodeIndices.size();
}

int NumSelectedLinks() {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_None);
  const ImNodesEditorContext& editor = EditorContextGet();
  return editor.SelectedLinkIndices.size();
}

void GetSelectedNodes(int* node_ids) {
  IM_ASSERT(node_ids != nullptr);

  const ImNodesEditorContext& editor = EditorContextGet();
  for (int i = 0; i < editor.SelectedNodeIndices.size(); ++i) {
    const int node_idx = editor.SelectedNodeIndices[i];
    node_ids[i] = editor.Nodes.Pool[node_idx].Id;
  }
}

void GetSelectedLinks(int* link_ids) {
  IM_ASSERT(link_ids != nullptr);

  const ImNodesEditorContext& editor = EditorContextGet();
  for (int i = 0; i < editor.SelectedLinkIndices.size(); ++i) {
    const int link_idx = editor.SelectedLinkIndices[i];
    link_ids[i] = editor.Links.Pool[link_idx].Id;
  }
}

void ClearNodeSelection() {
  ImNodesEditorContext& editor = EditorContextGet();
  editor.SelectedNodeIndices.clear();
}

void ClearNodeSelection(int node_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  ClearObjectSelection(editor.Nodes, editor.SelectedNodeIndices, node_id);
}

void ClearLinkSelection() {
  ImNodesEditorContext& editor = EditorContextGet();
  editor.SelectedLinkIndices.clear();
}

void ClearLinkSelection(int link_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  ClearObjectSelection(editor.Links, editor.SelectedLinkIndices, link_id);
}

void SelectNode(int node_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  SelectObject(editor.Nodes, editor.SelectedNodeIndices, node_id);
}

void SelectLink(int link_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  SelectObject(editor.Links, editor.SelectedLinkIndices, link_id);
}

bool IsNodeSelected(int node_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  return IsObjectSelected(editor.Nodes, editor.SelectedNodeIndices, node_id);
}

bool IsLinkSelected(int link_id) {
  ImNodesEditorContext& editor = EditorContextGet();
  return IsObjectSelected(editor.Links, editor.SelectedLinkIndices, link_id);
}

bool IsAttributeActive() {
  IM_ASSERT((GImNodes->CurrentScope & ImNodesScope_Node) != 0);

  if (!GImNodes->ActiveAttribute) {
    return false;
  }

  return GImNodes->ActiveAttributeId == GImNodes->CurrentAttributeId;
}

bool IsAnyAttributeActive(int* const attribute_id) {
  IM_ASSERT((GImNodes->CurrentScope & (ImNodesScope_Node | ImNodesScope_Attribute)) == 0);

  if (!GImNodes->ActiveAttribute) {
    return false;
  }

  if (attribute_id != nullptr) {
    *attribute_id = GImNodes->ActiveAttributeId;
  }

  return true;
}

bool IsLinkStarted(int* const started_at_id) {
  // Call this function after EndNodeEditor()!
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_None);
  IM_ASSERT(started_at_id != nullptr);

  const bool is_started = (GImNodes->ImNodesUIState & ImNodesUIState_LinkStarted) != 0;
  if (is_started) {
    const ImNodesEditorContext& editor = EditorContextGet();
    const int pin_idx = editor.ClickInteraction.LinkCreation.StartPinIdx;
    *started_at_id = editor.Pins.Pool[pin_idx].Id;
  }

  return is_started;
}

bool IsLinkDropped(int* const started_at_id, const bool including_detached_links) {
  // Call this function after EndNodeEditor()!
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_None);

  const ImNodesEditorContext& editor = EditorContextGet();

  const bool link_dropped =
      (GImNodes->ImNodesUIState & ImNodesUIState_LinkDropped) != 0 &&
      (including_detached_links ||
          editor.ClickInteraction.LinkCreation.Type != ImNodesLinkCreationType_FromDetach);

  if (link_dropped && (started_at_id != nullptr)) {
    const int pin_idx = editor.ClickInteraction.LinkCreation.StartPinIdx;
    *started_at_id = editor.Pins.Pool[pin_idx].Id;
  }

  return link_dropped;
}

bool IsLinkCreated(
    int* const started_at_pin_id, int* const ended_at_pin_id, bool* const created_from_snap) {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_None);
  IM_ASSERT(started_at_pin_id != nullptr);
  IM_ASSERT(ended_at_pin_id != nullptr);

  const bool is_created = (GImNodes->ImNodesUIState & ImNodesUIState_LinkCreated) != 0;

  if (is_created) {
    const ImNodesEditorContext& editor = EditorContextGet();
    const int start_idx = editor.ClickInteraction.LinkCreation.StartPinIdx;
    const int end_idx = editor.ClickInteraction.LinkCreation.EndPinIdx.Value();
    const ImPinData& start_pin = editor.Pins.Pool[start_idx];
    const ImPinData& end_pin = editor.Pins.Pool[end_idx];

    if (start_pin.Type == ImNodesAttributeType_Output) {
      *started_at_pin_id = start_pin.Id;
      *ended_at_pin_id = end_pin.Id;
    } else {
      *started_at_pin_id = end_pin.Id;
      *ended_at_pin_id = start_pin.Id;
    }

    if (created_from_snap != nullptr) {
      *created_from_snap = editor.ClickInteraction.Type == ImNodesClickInteractionType_LinkCreation;
    }
  }

  return is_created;
}

bool IsLinkCreated(int* started_at_node_id,
    int* started_at_pin_id,
    int* ended_at_node_id,
    int* ended_at_pin_id,
    bool* created_from_snap) {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_None);
  IM_ASSERT(started_at_node_id != nullptr);
  IM_ASSERT(started_at_pin_id != nullptr);
  IM_ASSERT(ended_at_node_id != nullptr);
  IM_ASSERT(ended_at_pin_id != nullptr);

  const bool is_created = (GImNodes->ImNodesUIState & ImNodesUIState_LinkCreated) != 0;

  if (is_created) {
    const ImNodesEditorContext& editor = EditorContextGet();
    const int start_idx = editor.ClickInteraction.LinkCreation.StartPinIdx;
    const int end_idx = editor.ClickInteraction.LinkCreation.EndPinIdx.Value();
    const ImPinData& start_pin = editor.Pins.Pool[start_idx];
    const ImNodeData& start_node = editor.Nodes.Pool[start_pin.ParentNodeIdx];
    const ImPinData& end_pin = editor.Pins.Pool[end_idx];
    const ImNodeData& end_node = editor.Nodes.Pool[end_pin.ParentNodeIdx];

    if (start_pin.Type == ImNodesAttributeType_Output) {
      *started_at_pin_id = start_pin.Id;
      *started_at_node_id = start_node.Id;
      *ended_at_pin_id = end_pin.Id;
      *ended_at_node_id = end_node.Id;
    } else {
      *started_at_pin_id = end_pin.Id;
      *started_at_node_id = end_node.Id;
      *ended_at_pin_id = start_pin.Id;
      *ended_at_node_id = start_node.Id;
    }

    if (created_from_snap != nullptr) {
      *created_from_snap = editor.ClickInteraction.Type == ImNodesClickInteractionType_LinkCreation;
    }
  }

  return is_created;
}

bool IsLinkDestroyed(int* const link_id) {
  IM_ASSERT(GImNodes->CurrentScope == ImNodesScope_None);

  const bool link_destroyed = GImNodes->DeletedLinkIdx.HasValue();
  if (link_destroyed) {
    const ImNodesEditorContext& editor = EditorContextGet();
    const int link_idx = GImNodes->DeletedLinkIdx.Value();
    *link_id = editor.Links.Pool[link_idx].Id;
  }

  return link_destroyed;
}

namespace {
void NodeLineHandler(ImNodesEditorContext& editor, const char* const line) {
  int id{};
  int x{};
  int y{};
  if (sscanf(line, "[node.%i", &id) == 1) {
    const int node_idx = ObjectPoolFindOrCreateIndex(editor.Nodes, id);
    GImNodes->CurrentNodeIdx = node_idx;
    ImNodeData& node = editor.Nodes.Pool[node_idx];
    node.Id = id;
  } else if (sscanf(line, "origin=%i,%i", &x, &y) == 2) {
    ImNodeData& node = editor.Nodes.Pool[GImNodes->CurrentNodeIdx];
    node.Origin = SnapOriginToGrid(ImVec2((float)x, (float)y));
  }
}

void EditorLineHandler(ImNodesEditorContext& editor, const char* const line) {
  (void)sscanf(line, "panning=%f,%f", &editor.Panning.x, &editor.Panning.y);
}
}  // namespace

const char* SaveCurrentEditorStateToIniString(size_t* const data_size) {
  return SaveEditorStateToIniString(&EditorContextGet(), data_size);
}

const char* SaveEditorStateToIniString(
    const ImNodesEditorContext* const editor_ptr, size_t* const data_size) {
  IM_ASSERT(editor_ptr != nullptr);
  const ImNodesEditorContext& editor = *editor_ptr;

  GImNodes->TextBuffer.clear();
  // TODO: check to make sure that the estimate is the upper bound of element
  GImNodes->TextBuffer.reserve(64 * editor.Nodes.Pool.size());

  GImNodes->TextBuffer.appendf("[editor]\npanning=%f,%f\n", editor.Panning.x, editor.Panning.y);

  for (int i = 0; i < editor.Nodes.Pool.size(); i++) {
    if (editor.Nodes.InUse[i]) {
      const ImNodeData& node = editor.Nodes.Pool[i];
      GImNodes->TextBuffer.appendf("\n[node.%d]\n", node.Id);
      GImNodes->TextBuffer.appendf("origin=%f,%f\n", node.Origin.x, node.Origin.y);
    }
  }

  if (data_size != nullptr) {
    *data_size = GImNodes->TextBuffer.size();
  }

  return GImNodes->TextBuffer.c_str();
}

void LoadCurrentEditorStateFromIniString(const char* const data, const size_t data_size) {
  LoadEditorStateFromIniString(&EditorContextGet(), data, data_size);
}

void LoadEditorStateFromIniString(
    ImNodesEditorContext* const editor_ptr, const char* const data, const size_t data_size) {
  if (data_size == 0U) {
    return;
  }

  ImNodesEditorContext& editor = editor_ptr == nullptr ? EditorContextGet() : *editor_ptr;

  char* buf = (char*)ImGui::MemAlloc(data_size + 1);
  const char* buf_end = buf + data_size;
  memcpy(buf, data, data_size);
  buf[data_size] = 0;

  void (*line_handler)(ImNodesEditorContext&, const char*);
  line_handler = nullptr;
  char* line_end = nullptr;
  for (char* line = buf; line < buf_end; line = line_end + 1) {
    while (*line == '\n' || *line == '\r') {
      line++;
    }
    line_end = line;
    while (line_end < buf_end && *line_end != '\n' && *line_end != '\r') {
      line_end++;
    }
    line_end[0] = 0;

    if (*line == ';' || *line == '\0') {
      continue;
    }

    if (line[0] == '[' && line_end[-1] == ']') {
      line_end[-1] = 0;
      if (strncmp(line + 1, "node", 4) == 0) {
        line_handler = NodeLineHandler;
      } else if (strcmp(line + 1, "editor") == 0) {
        line_handler = EditorLineHandler;
      }
    }

    if (line_handler != nullptr) {
      line_handler(editor, line);
    }
  }
  ImGui::MemFree(buf);
}

void SaveCurrentEditorStateToIniFile(const char* const file_name) {
  SaveEditorStateToIniFile(&EditorContextGet(), file_name);
}

void SaveEditorStateToIniFile(
    const ImNodesEditorContext* const editor, const char* const file_name) {
  size_t data_size = 0U;
  const char* data = SaveEditorStateToIniString(editor, &data_size);
  FILE* file = ImFileOpen(file_name, "wt");
  if (file == nullptr) {
    return;
  }

  fwrite(data, sizeof(char), data_size, file);
  fclose(file);
}

void LoadCurrentEditorStateFromIniFile(const char* const file_name) {
  LoadEditorStateFromIniFile(&EditorContextGet(), file_name);
}

void LoadEditorStateFromIniFile(ImNodesEditorContext* const editor, const char* const file_name) {
  size_t data_size = 0U;
  char* file_data = (char*)ImFileLoadToMemory(file_name, "rb", &data_size);

  if (file_data == nullptr) {
    return;
  }

  LoadEditorStateFromIniString(editor, file_data, data_size);
  ImGui::MemFree(file_data);
}
}  // namespace ImNodes
